linux-stable.git/mm, branch v6.1.2 Linux kernel stable tree mm/gup: disallow FOLL_FORCE|FOLL_WRITE on hugetlb mappings 2022-12-31T12:33:11+00:00 David Hildenbrand david@redhat.com 2022-10-31T15:25:24+00:00 5cfb9a60ed2d5afed6500078ac3a25fd4d71c1aa commit f347454d034184b4f0a2caf6e14daf7848cea01c upstream. hugetlb does not support fake write-faults (write faults without write permissions). However, we are currently able to trigger a FAULT_FLAG_WRITE fault on a VMA without VM_WRITE. If we'd ever want to support FOLL_FORCE|FOLL_WRITE, we'd have to teach hugetlb to: (1) Leave the page mapped R/O after the fake write-fault, like maybe_mkwrite() does. (2) Allow writing to an exclusive anon page that's mapped R/O when FOLL_FORCE is set, like can_follow_write_pte(). E.g., __follow_hugetlb_must_fault() needs adjustment. For now, it's not clear if that added complexity is really required. History tolds us that FOLL_FORCE is dangerous and that we better limit its use to a bare minimum. -------------------------------------------------------------------------- #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #include <errno.h> #include <stdint.h> #include <sys/mman.h> #include <linux/mman.h> int main(int argc, char **argv) { char *map; int mem_fd; map = mmap(NULL, 2 * 1024 * 1024u, PROT_READ, MAP_PRIVATE|MAP_ANON|MAP_HUGETLB|MAP_HUGE_2MB, -1, 0); if (map == MAP_FAILED) { fprintf(stderr, "mmap() failed: %d\n", errno); return 1; } mem_fd = open("/proc/self/mem", O_RDWR); if (mem_fd < 0) { fprintf(stderr, "open(/proc/self/mem) failed: %d\n", errno); return 1; } if (pwrite(mem_fd, "0", 1, (uintptr_t) map) == 1) { fprintf(stderr, "write() succeeded, which is unexpected\n"); return 1; } printf("write() failed as expected: %d\n", errno); return 0; } -------------------------------------------------------------------------- Fortunately, we have a sanity check in hugetlb_wp() in place ever since commit 1d8d14641fd9 ("mm/hugetlb: support write-faults in shared mappings"), that bails out instead of silently mapping a page writable in a !PROT_WRITE VMA. Consequently, above reproducer triggers a warning, similar to the one reported by szsbot: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 3612 at mm/hugetlb.c:5313 hugetlb_wp+0x20a/0x1af0 mm/hugetlb.c:5313 Modules linked in: CPU: 1 PID: 3612 Comm: syz-executor250 Not tainted 6.1.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022 RIP: 0010:hugetlb_wp+0x20a/0x1af0 mm/hugetlb.c:5313 Code: ea 03 80 3c 02 00 0f 85 31 14 00 00 49 8b 5f 20 31 ff 48 89 dd 83 e5 02 48 89 ee e8 70 ab b7 ff 48 85 ed 75 5b e8 76 ae b7 ff <0f> 0b 41 bd 40 00 00 00 e8 69 ae b7 ff 48 b8 00 00 00 00 00 fc ff RSP: 0018:ffffc90003caf620 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000008640070 RCX: 0000000000000000 RDX: ffff88807b963a80 RSI: ffffffff81c4ed2a RDI: 0000000000000007 RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000000 R11: 000000000008c07e R12: ffff888023805800 R13: 0000000000000000 R14: ffffffff91217f38 R15: ffff88801d4b0360 FS: 0000555555bba300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fff7a47a1b8 CR3: 000000002378d000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> hugetlb_no_page mm/hugetlb.c:5755 [inline] hugetlb_fault+0x19cc/0x2060 mm/hugetlb.c:5874 follow_hugetlb_page+0x3f3/0x1850 mm/hugetlb.c:6301 __get_user_pages+0x2cb/0xf10 mm/gup.c:1202 __get_user_pages_locked mm/gup.c:1434 [inline] __get_user_pages_remote+0x18f/0x830 mm/gup.c:2187 get_user_pages_remote+0x84/0xc0 mm/gup.c:2260 __access_remote_vm+0x287/0x6b0 mm/memory.c:5517 ptrace_access_vm+0x181/0x1d0 kernel/ptrace.c:61 generic_ptrace_pokedata kernel/ptrace.c:1323 [inline] ptrace_request+0xb46/0x10c0 kernel/ptrace.c:1046 arch_ptrace+0x36/0x510 arch/x86/kernel/ptrace.c:828 __do_sys_ptrace kernel/ptrace.c:1296 [inline] __se_sys_ptrace kernel/ptrace.c:1269 [inline] __x64_sys_ptrace+0x178/0x2a0 kernel/ptrace.c:1269 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] So let's silence that warning by teaching GUP code that FOLL_FORCE -- so far -- does not apply to hugetlb. Note that FOLL_FORCE for read-access seems to be working as expected. The assumption is that this has been broken forever, only ever since above commit, we actually detect the wrong handling and WARN_ON_ONCE(). I assume this has been broken at least since 2014, when mm/gup.c came to life. I failed to come up with a suitable Fixes tag quickly. Link: https://lkml.kernel.org/r/20221031152524.173644-1-david@redhat.com Fixes: 1d8d14641fd9 ("mm/hugetlb: support write-faults in shared mappings") Signed-off-by: David Hildenbrand <david@redhat.com> Reported-by: <syzbot+f0b97304ef90f0d0b1dc@syzkaller.appspotmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f347454d034184b4f0a2caf6e14daf7848cea01c upstream.

hugetlb does not support fake write-faults (write faults without write
permissions).  However, we are currently able to trigger a
FAULT_FLAG_WRITE fault on a VMA without VM_WRITE.

If we'd ever want to support FOLL_FORCE|FOLL_WRITE, we'd have to teach
hugetlb to:

(1) Leave the page mapped R/O after the fake write-fault, like
    maybe_mkwrite() does.
(2) Allow writing to an exclusive anon page that's mapped R/O when
    FOLL_FORCE is set, like can_follow_write_pte(). E.g.,
    __follow_hugetlb_must_fault() needs adjustment.

For now, it's not clear if that added complexity is really required.
History tolds us that FOLL_FORCE is dangerous and that we better limit its
use to a bare minimum.

--------------------------------------------------------------------------
  #include <stdio.h>
  #include <stdlib.h>
  #include <fcntl.h>
  #include <unistd.h>
  #include <errno.h>
  #include <stdint.h>
  #include <sys/mman.h>
  #include <linux/mman.h>

  int main(int argc, char **argv)
  {
          char *map;
          int mem_fd;

          map = mmap(NULL, 2 * 1024 * 1024u, PROT_READ,
                     MAP_PRIVATE|MAP_ANON|MAP_HUGETLB|MAP_HUGE_2MB, -1, 0);
          if (map == MAP_FAILED) {
                  fprintf(stderr, "mmap() failed: %d\n", errno);
                  return 1;
          }

          mem_fd = open("/proc/self/mem", O_RDWR);
          if (mem_fd < 0) {
                  fprintf(stderr, "open(/proc/self/mem) failed: %d\n", errno);
                  return 1;
          }

          if (pwrite(mem_fd, "0", 1, (uintptr_t) map) == 1) {
                  fprintf(stderr, "write() succeeded, which is unexpected\n");
                  return 1;
          }

          printf("write() failed as expected: %d\n", errno);
          return 0;
  }
--------------------------------------------------------------------------

Fortunately, we have a sanity check in hugetlb_wp() in place ever since
commit 1d8d14641fd9 ("mm/hugetlb: support write-faults in shared
mappings"), that bails out instead of silently mapping a page writable in
a !PROT_WRITE VMA.

Consequently, above reproducer triggers a warning, similar to the one
reported by szsbot:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 3612 at mm/hugetlb.c:5313 hugetlb_wp+0x20a/0x1af0 mm/hugetlb.c:5313
Modules linked in:
CPU: 1 PID: 3612 Comm: syz-executor250 Not tainted 6.1.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:hugetlb_wp+0x20a/0x1af0 mm/hugetlb.c:5313
Code: ea 03 80 3c 02 00 0f 85 31 14 00 00 49 8b 5f 20 31 ff 48 89 dd 83 e5 02 48 89 ee e8 70 ab b7 ff 48 85 ed 75 5b e8 76 ae b7 ff <0f> 0b 41 bd 40 00 00 00 e8 69 ae b7 ff 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc90003caf620 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000008640070 RCX: 0000000000000000
RDX: ffff88807b963a80 RSI: ffffffff81c4ed2a RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 000000000008c07e R12: ffff888023805800
R13: 0000000000000000 R14: ffffffff91217f38 R15: ffff88801d4b0360
FS:  0000555555bba300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff7a47a1b8 CR3: 000000002378d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 hugetlb_no_page mm/hugetlb.c:5755 [inline]
 hugetlb_fault+0x19cc/0x2060 mm/hugetlb.c:5874
 follow_hugetlb_page+0x3f3/0x1850 mm/hugetlb.c:6301
 __get_user_pages+0x2cb/0xf10 mm/gup.c:1202
 __get_user_pages_locked mm/gup.c:1434 [inline]
 __get_user_pages_remote+0x18f/0x830 mm/gup.c:2187
 get_user_pages_remote+0x84/0xc0 mm/gup.c:2260
 __access_remote_vm+0x287/0x6b0 mm/memory.c:5517
 ptrace_access_vm+0x181/0x1d0 kernel/ptrace.c:61
 generic_ptrace_pokedata kernel/ptrace.c:1323 [inline]
 ptrace_request+0xb46/0x10c0 kernel/ptrace.c:1046
 arch_ptrace+0x36/0x510 arch/x86/kernel/ptrace.c:828
 __do_sys_ptrace kernel/ptrace.c:1296 [inline]
 __se_sys_ptrace kernel/ptrace.c:1269 [inline]
 __x64_sys_ptrace+0x178/0x2a0 kernel/ptrace.c:1269
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
[...]

So let's silence that warning by teaching GUP code that FOLL_FORCE -- so
far -- does not apply to hugetlb.

Note that FOLL_FORCE for read-access seems to be working as expected.  The
assumption is that this has been broken forever, only ever since above
commit, we actually detect the wrong handling and WARN_ON_ONCE().

I assume this has been broken at least since 2014, when mm/gup.c came to
life.  I failed to come up with a suitable Fixes tag quickly.

Link: https://lkml.kernel.org/r/20221031152524.173644-1-david@redhat.com
Fixes: 1d8d14641fd9 ("mm/hugetlb: support write-faults in shared mappings")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: <syzbot+f0b97304ef90f0d0b1dc@syzkaller.appspotmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge tag 'mm-hotfixes-stable-2022-12-10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2022-12-11T01:10:52+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-12-11T01:10:52+00:00 4cee37b3a4e68c42b867c87a6218e11bc571ba66 Pull misc fixes from Andrew Morton: "Nine hotfixes. Six for MM, three for other areas. Four of these patches address post-6.0 issues" * tag 'mm-hotfixes-stable-2022-12-10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: memcg: fix possible use-after-free in memcg_write_event_control() MAINTAINERS: update Muchun Song's email mm/gup: fix gup_pud_range() for dax mmap: fix do_brk_flags() modifying obviously incorrect VMAs mm/swap: fix SWP_PFN_BITS with CONFIG_PHYS_ADDR_T_64BIT on 32bit tmpfs: fix data loss from failed fallocate kselftests: cgroup: update kmem test precision tolerance mm: do not BUG_ON missing brk mapping, because userspace can unmap it mailmap: update Matti Vaittinen's email address 
Pull misc fixes from Andrew Morton:
 "Nine hotfixes.

  Six for MM, three for other areas. Four of these patches address
  post-6.0 issues"

* tag 'mm-hotfixes-stable-2022-12-10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  memcg: fix possible use-after-free in memcg_write_event_control()
  MAINTAINERS: update Muchun Song's email
  mm/gup: fix gup_pud_range() for dax
  mmap: fix do_brk_flags() modifying obviously incorrect VMAs
  mm/swap: fix SWP_PFN_BITS with CONFIG_PHYS_ADDR_T_64BIT on 32bit
  tmpfs: fix data loss from failed fallocate
  kselftests: cgroup: update kmem test precision tolerance
  mm: do not BUG_ON missing brk mapping, because userspace can unmap it
  mailmap: update Matti Vaittinen's email address
memcg: fix possible use-after-free in memcg_write_event_control() 2022-12-10T02:41:17+00:00 Tejun Heo tj@kernel.org 2022-12-08T02:53:15+00:00 4a7ba45b1a435e7097ca0f79a847d0949d0eb088 memcg_write_event_control() accesses the dentry->d_name of the specified control fd to route the write call. As a cgroup interface file can't be renamed, it's safe to access d_name as long as the specified file is a regular cgroup file. Also, as these cgroup interface files can't be removed before the directory, it's safe to access the parent too. Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a call to __file_cft() which verified that the specified file is a regular cgroupfs file before further accesses. The cftype pointer returned from __file_cft() was no longer necessary and the commit inadvertently dropped the file type check with it allowing any file to slip through. With the invarients broken, the d_name and parent accesses can now race against renames and removals of arbitrary files and cause use-after-free's. Fix the bug by resurrecting the file type check in __file_cft(). Now that cgroupfs is implemented through kernfs, checking the file operations needs to go through a layer of indirection. Instead, let's check the superblock and dentry type. Link: https://lkml.kernel.org/r/Y5FRm/cfcKPGzWwl@slm.duckdns.org Fixes: 347c4a874710 ("memcg: remove cgroup_event->cft") Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jann Horn <jannh@google.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: <stable@vger.kernel.org> [3.14+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
memcg_write_event_control() accesses the dentry->d_name of the specified
control fd to route the write call.  As a cgroup interface file can't be
renamed, it's safe to access d_name as long as the specified file is a
regular cgroup file.  Also, as these cgroup interface files can't be
removed before the directory, it's safe to access the parent too.

Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a
call to __file_cft() which verified that the specified file is a regular
cgroupfs file before further accesses.  The cftype pointer returned from
__file_cft() was no longer necessary and the commit inadvertently dropped
the file type check with it allowing any file to slip through.  With the
invarients broken, the d_name and parent accesses can now race against
renames and removals of arbitrary files and cause use-after-free's.

Fix the bug by resurrecting the file type check in __file_cft().  Now that
cgroupfs is implemented through kernfs, checking the file operations needs
to go through a layer of indirection.  Instead, let's check the superblock
and dentry type.

Link: https://lkml.kernel.org/r/Y5FRm/cfcKPGzWwl@slm.duckdns.org
Fixes: 347c4a874710 ("memcg: remove cgroup_event->cft")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>	[3.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/gup: fix gup_pud_range() for dax 2022-12-10T02:41:17+00:00 John Starks jostarks@microsoft.com 2022-12-07T06:00:53+00:00 fcd0ccd836ffad73d98a66f6fea7b16f735ea920 For dax pud, pud_huge() returns true on x86. So the function works as long as hugetlb is configured. However, dax doesn't depend on hugetlb. Commit 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax") fixed devmap-backed huge PMDs, but missed devmap-backed huge PUDs. Fix this as well. This fixes the below kernel panic: general protection fault, probably for non-canonical address 0x69e7c000cc478: 0000 [#1] SMP < snip > Call Trace: <TASK> get_user_pages_fast+0x1f/0x40 iov_iter_get_pages+0xc6/0x3b0 ? mempool_alloc+0x5d/0x170 bio_iov_iter_get_pages+0x82/0x4e0 ? bvec_alloc+0x91/0xc0 ? bio_alloc_bioset+0x19a/0x2a0 blkdev_direct_IO+0x282/0x480 ? __io_complete_rw_common+0xc0/0xc0 ? filemap_range_has_page+0x82/0xc0 generic_file_direct_write+0x9d/0x1a0 ? inode_update_time+0x24/0x30 __generic_file_write_iter+0xbd/0x1e0 blkdev_write_iter+0xb4/0x150 ? io_import_iovec+0x8d/0x340 io_write+0xf9/0x300 io_issue_sqe+0x3c3/0x1d30 ? sysvec_reschedule_ipi+0x6c/0x80 __io_queue_sqe+0x33/0x240 ? fget+0x76/0xa0 io_submit_sqes+0xe6a/0x18d0 ? __fget_light+0xd1/0x100 __x64_sys_io_uring_enter+0x199/0x880 ? __context_tracking_enter+0x1f/0x70 ? irqentry_exit_to_user_mode+0x24/0x30 ? irqentry_exit+0x1d/0x30 ? __context_tracking_exit+0xe/0x70 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fc97c11a7be < snip > </TASK> ---[ end trace 48b2e0e67debcaeb ]--- RIP: 0010:internal_get_user_pages_fast+0x340/0x990 < snip > Kernel panic - not syncing: Fatal exception Kernel Offset: disabled Link: https://lkml.kernel.org/r/1670392853-28252-1-git-send-email-ssengar@linux.microsoft.com Fixes: 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax") Signed-off-by: John Starks <jostarks@microsoft.com> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com> Cc: Jan Kara <jack@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: David Hildenbrand <david@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
For dax pud, pud_huge() returns true on x86. So the function works as long
as hugetlb is configured. However, dax doesn't depend on hugetlb.
Commit 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax") fixed
devmap-backed huge PMDs, but missed devmap-backed huge PUDs. Fix this as
well.

This fixes the below kernel panic:

general protection fault, probably for non-canonical address 0x69e7c000cc478: 0000 [#1] SMP
	< snip >
Call Trace:
<TASK>
get_user_pages_fast+0x1f/0x40
iov_iter_get_pages+0xc6/0x3b0
? mempool_alloc+0x5d/0x170
bio_iov_iter_get_pages+0x82/0x4e0
? bvec_alloc+0x91/0xc0
? bio_alloc_bioset+0x19a/0x2a0
blkdev_direct_IO+0x282/0x480
? __io_complete_rw_common+0xc0/0xc0
? filemap_range_has_page+0x82/0xc0
generic_file_direct_write+0x9d/0x1a0
? inode_update_time+0x24/0x30
__generic_file_write_iter+0xbd/0x1e0
blkdev_write_iter+0xb4/0x150
? io_import_iovec+0x8d/0x340
io_write+0xf9/0x300
io_issue_sqe+0x3c3/0x1d30
? sysvec_reschedule_ipi+0x6c/0x80
__io_queue_sqe+0x33/0x240
? fget+0x76/0xa0
io_submit_sqes+0xe6a/0x18d0
? __fget_light+0xd1/0x100
__x64_sys_io_uring_enter+0x199/0x880
? __context_tracking_enter+0x1f/0x70
? irqentry_exit_to_user_mode+0x24/0x30
? irqentry_exit+0x1d/0x30
? __context_tracking_exit+0xe/0x70
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fc97c11a7be
	< snip >
</TASK>
---[ end trace 48b2e0e67debcaeb ]---
RIP: 0010:internal_get_user_pages_fast+0x340/0x990
	< snip >
Kernel panic - not syncing: Fatal exception
Kernel Offset: disabled

Link: https://lkml.kernel.org/r/1670392853-28252-1-git-send-email-ssengar@linux.microsoft.com
Fixes: 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax")
Signed-off-by: John Starks <jostarks@microsoft.com>
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mmap: fix do_brk_flags() modifying obviously incorrect VMAs 2022-12-10T02:41:16+00:00 Liam Howlett liam.howlett@oracle.com 2022-12-05T19:23:17+00:00 6c28ca6485ddd7c5da171e479e3ebfbe661efc4d Add more sanity checks to the VMA that do_brk_flags() will expand. Ensure the VMA matches basic merge requirements within the function before calling can_vma_merge_after(). Drop the duplicate checks from vm_brk_flags() since they will be enforced later. The old code would expand file VMAs on brk(), which is functionally wrong and also dangerous in terms of locking because the brk() path isn't designed for file VMAs and therefore doesn't lock the file mapping. Checking can_vma_merge_after() ensures that new anonymous VMAs can't be merged into file VMAs. See https://lore.kernel.org/linux-mm/CAG48ez1tJZTOjS_FjRZhvtDA-STFmdw8PEizPDwMGFd_ui0Nrw@mail.gmail.com/ Link: https://lkml.kernel.org/r/20221205192304.1957418-1-Liam.Howlett@oracle.com Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()") Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Suggested-by: Jann Horn <jannh@google.com> Cc: Jason A. Donenfeld <Jason@zx2c4.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: SeongJae Park <sj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Add more sanity checks to the VMA that do_brk_flags() will expand.  Ensure
the VMA matches basic merge requirements within the function before
calling can_vma_merge_after().

Drop the duplicate checks from vm_brk_flags() since they will be enforced
later.

The old code would expand file VMAs on brk(), which is functionally
wrong and also dangerous in terms of locking because the brk() path
isn't designed for file VMAs and therefore doesn't lock the file
mapping.  Checking can_vma_merge_after() ensures that new anonymous
VMAs can't be merged into file VMAs.

See https://lore.kernel.org/linux-mm/CAG48ez1tJZTOjS_FjRZhvtDA-STFmdw8PEizPDwMGFd_ui0Nrw@mail.gmail.com/

Link: https://lkml.kernel.org/r/20221205192304.1957418-1-Liam.Howlett@oracle.com
Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Suggested-by: Jann Horn <jannh@google.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
tmpfs: fix data loss from failed fallocate 2022-12-10T02:41:16+00:00 Hugh Dickins hughd@google.com 2022-12-05T00:51:50+00:00 44bcabd70cf1425b4243e02251c02b01638a8287 Fix tmpfs data loss when the fallocate system call is interrupted by a signal, or fails for some other reason. The partial folio handling in shmem_undo_range() forgot to consider this unfalloc case, and was liable to erase or truncate out data which had already been committed earlier. It turns out that none of the partial folio handling there is appropriate for the unfalloc case, which just wants to proceed to removal of whole folios: which find_get_entries() provides, even when partially covered. Original patch by Rui Wang. Link: https://lore.kernel.org/linux-mm/33b85d82.7764.1842e9ab207.Coremail.chenguoqic@163.com/ Link: https://lkml.kernel.org/r/a5dac112-cf4b-7af-a33-f386e347fd38@google.com Fixes: b9a8a4195c7d ("truncate,shmem: Handle truncates that split large folios") Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: Guoqi Chen <chenguoqic@163.com> Link: https://lore.kernel.org/all/20221101032248.819360-1-kernel@hev.cc/ Cc: Rui Wang <kernel@hev.cc> Cc: Huacai Chen <chenhuacai@loongson.cn> Cc: Matthew Wilcox <willy@infradead.org> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Cc: <stable@vger.kernel.org> [5.17+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Fix tmpfs data loss when the fallocate system call is interrupted by a
signal, or fails for some other reason.  The partial folio handling in
shmem_undo_range() forgot to consider this unfalloc case, and was liable
to erase or truncate out data which had already been committed earlier.

It turns out that none of the partial folio handling there is appropriate
for the unfalloc case, which just wants to proceed to removal of whole
folios: which find_get_entries() provides, even when partially covered.

Original patch by Rui Wang.

Link: https://lore.kernel.org/linux-mm/33b85d82.7764.1842e9ab207.Coremail.chenguoqic@163.com/
Link: https://lkml.kernel.org/r/a5dac112-cf4b-7af-a33-f386e347fd38@google.com
Fixes: b9a8a4195c7d ("truncate,shmem: Handle truncates that split large folios")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Guoqi Chen <chenguoqic@163.com>
  Link: https://lore.kernel.org/all/20221101032248.819360-1-kernel@hev.cc/
Cc: Rui Wang <kernel@hev.cc>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: <stable@vger.kernel.org>	[5.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: do not BUG_ON missing brk mapping, because userspace can unmap it 2022-12-10T02:41:16+00:00 Jason A. Donenfeld Jason@zx2c4.com 2022-12-02T16:27:24+00:00 f5ad5083404bb56c9de777dccb68c6672ef6487e The following program will trigger the BUG_ON that this patch removes, because the user can munmap() mm->brk: #include <sys/syscall.h> #include <sys/mman.h> #include <assert.h> #include <unistd.h> static void *brk_now(void) { return (void *)syscall(SYS_brk, 0); } static void brk_set(void *b) { assert(syscall(SYS_brk, b) != -1); } int main(int argc, char *argv[]) { void *b = brk_now(); brk_set(b + 4096); assert(munmap(b - 4096, 4096 * 2) == 0); brk_set(b); return 0; } Compile that with musl, since glibc actually uses brk(), and then execute it, and it'll hit this splat: kernel BUG at mm/mmap.c:229! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 12 PID: 1379 Comm: a.out Tainted: G S U 6.1.0-rc7+ #419 RIP: 0010:__do_sys_brk+0x2fc/0x340 Code: 00 00 4c 89 ef e8 04 d3 fe ff eb 9a be 01 00 00 00 4c 89 ff e8 35 e0 fe ff e9 6e ff ff ff 4d 89 a7 20> RSP: 0018:ffff888140bc7eb0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 00000000007e7000 RCX: ffff8881020fe000 RDX: ffff8881020fe001 RSI: ffff8881955c9b00 RDI: ffff8881955c9b08 RBP: 0000000000000000 R08: ffff8881955c9b00 R09: 00007ffc77844000 R10: 0000000000000000 R11: 0000000000000001 R12: 00000000007e8000 R13: 00000000007e8000 R14: 00000000007e7000 R15: ffff8881020fe000 FS: 0000000000604298(0000) GS:ffff88901f700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000603fe0 CR3: 000000015ba9a005 CR4: 0000000000770ee0 PKRU: 55555554 Call Trace: <TASK> do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x400678 Code: 10 4c 8d 41 08 4c 89 44 24 10 4c 8b 01 8b 4c 24 08 83 f9 2f 77 0a 4c 8d 4c 24 20 4c 01 c9 eb 05 48 8b> RSP: 002b:00007ffc77863890 EFLAGS: 00000212 ORIG_RAX: 000000000000000c RAX: ffffffffffffffda RBX: 000000000040031b RCX: 0000000000400678 RDX: 00000000004006a1 RSI: 00000000007e6000 RDI: 00000000007e7000 RBP: 00007ffc77863900 R08: 0000000000000000 R09: 00000000007e6000 R10: 00007ffc77863930 R11: 0000000000000212 R12: 00007ffc77863978 R13: 00007ffc77863988 R14: 0000000000000000 R15: 0000000000000000 </TASK> Instead, just return the old brk value if the original mapping has been removed. [akpm@linux-foundation.org: fix changelog, per Liam] Link: https://lkml.kernel.org/r/20221202162724.2009-1-Jason@zx2c4.com Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()") Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Will Deacon <will@kernel.org> Cc: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
The following program will trigger the BUG_ON that this patch removes,
because the user can munmap() mm->brk:

  #include <sys/syscall.h>
  #include <sys/mman.h>
  #include <assert.h>
  #include <unistd.h>

  static void *brk_now(void)
  {
    return (void *)syscall(SYS_brk, 0);
  }

  static void brk_set(void *b)
  {
    assert(syscall(SYS_brk, b) != -1);
  }

  int main(int argc, char *argv[])
  {
    void *b = brk_now();
    brk_set(b + 4096);
    assert(munmap(b - 4096, 4096 * 2) == 0);
    brk_set(b);
    return 0;
  }

Compile that with musl, since glibc actually uses brk(), and then
execute it, and it'll hit this splat:

  kernel BUG at mm/mmap.c:229!
  invalid opcode: 0000 [#1] PREEMPT SMP
  CPU: 12 PID: 1379 Comm: a.out Tainted: G S   U             6.1.0-rc7+ #419
  RIP: 0010:__do_sys_brk+0x2fc/0x340
  Code: 00 00 4c 89 ef e8 04 d3 fe ff eb 9a be 01 00 00 00 4c 89 ff e8 35 e0 fe ff e9 6e ff ff ff 4d 89 a7 20>
  RSP: 0018:ffff888140bc7eb0 EFLAGS: 00010246
  RAX: 0000000000000000 RBX: 00000000007e7000 RCX: ffff8881020fe000
  RDX: ffff8881020fe001 RSI: ffff8881955c9b00 RDI: ffff8881955c9b08
  RBP: 0000000000000000 R08: ffff8881955c9b00 R09: 00007ffc77844000
  R10: 0000000000000000 R11: 0000000000000001 R12: 00000000007e8000
  R13: 00000000007e8000 R14: 00000000007e7000 R15: ffff8881020fe000
  FS:  0000000000604298(0000) GS:ffff88901f700000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000603fe0 CR3: 000000015ba9a005 CR4: 0000000000770ee0
  PKRU: 55555554
  Call Trace:
   <TASK>
   do_syscall_64+0x2b/0x50
   entry_SYSCALL_64_after_hwframe+0x46/0xb0
  RIP: 0033:0x400678
  Code: 10 4c 8d 41 08 4c 89 44 24 10 4c 8b 01 8b 4c 24 08 83 f9 2f 77 0a 4c 8d 4c 24 20 4c 01 c9 eb 05 48 8b>
  RSP: 002b:00007ffc77863890 EFLAGS: 00000212 ORIG_RAX: 000000000000000c
  RAX: ffffffffffffffda RBX: 000000000040031b RCX: 0000000000400678
  RDX: 00000000004006a1 RSI: 00000000007e6000 RDI: 00000000007e7000
  RBP: 00007ffc77863900 R08: 0000000000000000 R09: 00000000007e6000
  R10: 00007ffc77863930 R11: 0000000000000212 R12: 00007ffc77863978
  R13: 00007ffc77863988 R14: 0000000000000000 R15: 0000000000000000
   </TASK>

Instead, just return the old brk value if the original mapping has been
removed.

[akpm@linux-foundation.org: fix changelog, per Liam]
Link: https://lkml.kernel.org/r/20221202162724.2009-1-Jason@zx2c4.com
Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
memcg: Fix possible use-after-free in memcg_write_event_control() 2022-12-08T18:40:58+00:00 Tejun Heo tj@kernel.org 2022-12-08T02:53:15+00:00 fbf8321238bac04368f57af572e05a9c01347a0b memcg_write_event_control() accesses the dentry->d_name of the specified control fd to route the write call. As a cgroup interface file can't be renamed, it's safe to access d_name as long as the specified file is a regular cgroup file. Also, as these cgroup interface files can't be removed before the directory, it's safe to access the parent too. Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a call to __file_cft() which verified that the specified file is a regular cgroupfs file before further accesses. The cftype pointer returned from __file_cft() was no longer necessary and the commit inadvertently dropped the file type check with it allowing any file to slip through. With the invarients broken, the d_name and parent accesses can now race against renames and removals of arbitrary files and cause use-after-free's. Fix the bug by resurrecting the file type check in __file_cft(). Now that cgroupfs is implemented through kernfs, checking the file operations needs to go through a layer of indirection. Instead, let's check the superblock and dentry type. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 347c4a874710 ("memcg: remove cgroup_event->cft") Cc: stable@kernel.org # v3.14+ Reported-by: Jann Horn <jannh@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
memcg_write_event_control() accesses the dentry->d_name of the specified
control fd to route the write call.  As a cgroup interface file can't be
renamed, it's safe to access d_name as long as the specified file is a
regular cgroup file.  Also, as these cgroup interface files can't be
removed before the directory, it's safe to access the parent too.

Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a
call to __file_cft() which verified that the specified file is a regular
cgroupfs file before further accesses.  The cftype pointer returned from
__file_cft() was no longer necessary and the commit inadvertently
dropped the file type check with it allowing any file to slip through.
With the invarients broken, the d_name and parent accesses can now race
against renames and removals of arbitrary files and cause
use-after-free's.

Fix the bug by resurrecting the file type check in __file_cft().  Now
that cgroupfs is implemented through kernfs, checking the file
operations needs to go through a layer of indirection.  Instead, let's
check the superblock and dentry type.

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 347c4a874710 ("memcg: remove cgroup_event->cft")
Cc: stable@kernel.org # v3.14+
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Revert "mm: align larger anonymous mappings on THP boundaries" 2022-12-04T20:51:59+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-12-04T20:51:59+00:00 0ba09b1733878afe838fe35c310715fda3d46428 This reverts commit f35b5d7d676e59e401690b678cd3cfec5e785c23. It has been reported to cause huge performance regressions on some loads (will-it-scale.per_process_ops, but also building the kernel with clang). The commit did speed up gcc builds by a small amount, so it's not an unambiguous regression, but until the big regressions are understood, let's revert it. Reported-by: kernel test robot <yujie.liu@intel.com> Link: https://lore.kernel.org/r/202210181535.7144dd15-yujie.liu@intel.com Reported-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/lkml/Y1DNQaoPWxE%2BrGce@dev-arch.thelio-3990X/ Cc: Huang, Ying <ying.huang@intel.com> Cc: Rik van Riel <riel@surriel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
This reverts commit f35b5d7d676e59e401690b678cd3cfec5e785c23.

It has been reported to cause huge performance regressions on some loads
(will-it-scale.per_process_ops, but also building the kernel with
clang).

The commit did speed up gcc builds by a small amount, so it's not an
unambiguous regression, but until the big regressions are understood,
let's revert it.

Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/r/202210181535.7144dd15-yujie.liu@intel.com
Reported-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/lkml/Y1DNQaoPWxE%2BrGce@dev-arch.thelio-3990X/
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'mm-hotfixes-stable-2022-12-02' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2022-12-02T21:39:38+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-12-02T21:39:38+00:00 bdaa78c6aa861f0e8c612a0b2272423d92f0071c Pull misc hotfixes from Andrew Morton: "15 hotfixes, 11 marked cc:stable. Only three or four of the latter address post-6.0 issues, which is hopefully a sign that things are converging" * tag 'mm-hotfixes-stable-2022-12-02' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: revert "kbuild: fix -Wimplicit-function-declaration in license_is_gpl_compatible" Kconfig.debug: provide a little extra FRAME_WARN leeway when KASAN is enabled drm/amdgpu: temporarily disable broken Clang builds due to blown stack-frame mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths mm/khugepaged: fix GUP-fast interaction by sending IPI mm/khugepaged: take the right locks for page table retraction mm: migrate: fix THP's mapcount on isolation mm: introduce arch_has_hw_nonleaf_pmd_young() mm: add dummy pmd_young() for architectures not having it mm/damon/sysfs: fix wrong empty schemes assumption under online tuning in damon_sysfs_set_schemes() tools/vm/slabinfo-gnuplot: use "grep -E" instead of "egrep" nilfs2: fix NULL pointer dereference in nilfs_palloc_commit_free_entry() hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing madvise: use zap_page_range_single for madvise dontneed mm: replace VM_WARN_ON to pr_warn if the node is offline with __GFP_THISNODE 
Pull misc hotfixes from Andrew Morton:
 "15 hotfixes,  11 marked cc:stable.

  Only three or four of the latter address post-6.0 issues, which is
  hopefully a sign that things are converging"

* tag 'mm-hotfixes-stable-2022-12-02' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  revert "kbuild: fix -Wimplicit-function-declaration in license_is_gpl_compatible"
  Kconfig.debug: provide a little extra FRAME_WARN leeway when KASAN is enabled
  drm/amdgpu: temporarily disable broken Clang builds due to blown stack-frame
  mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths
  mm/khugepaged: fix GUP-fast interaction by sending IPI
  mm/khugepaged: take the right locks for page table retraction
  mm: migrate: fix THP's mapcount on isolation
  mm: introduce arch_has_hw_nonleaf_pmd_young()
  mm: add dummy pmd_young() for architectures not having it
  mm/damon/sysfs: fix wrong empty schemes assumption under online tuning in damon_sysfs_set_schemes()
  tools/vm/slabinfo-gnuplot: use "grep -E" instead of "egrep"
  nilfs2: fix NULL pointer dereference in nilfs_palloc_commit_free_entry()
  hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing
  madvise: use zap_page_range_single for madvise dontneed
  mm: replace VM_WARN_ON to pr_warn if the node is offline with __GFP_THISNODE