linux-stable.git/fs/proc, branch v4.19.151 Linux kernel stable tree proc: Use new_inode not new_inode_pseudo 2020-06-22T07:05:06+00:00 Eric W. Biederman ebiederm@xmission.com 2020-06-12T14:42:03+00:00 de13aebcf5a812fc9bd70fac7dd7a47bbf9cc3ef commit ef1548adada51a2f32ed7faef50aa465e1b4c5da upstream. Recently syzbot reported that unmounting proc when there is an ongoing inotify watch on the root directory of proc could result in a use after free when the watch is removed after the unmount of proc when the watcher exits. Commit 69879c01a0c3 ("proc: Remove the now unnecessary internal mount of proc") made it easier to unmount proc and allowed syzbot to see the problem, but looking at the code it has been around for a long time. Looking at the code the fsnotify watch should have been removed by fsnotify_sb_delete in generic_shutdown_super. Unfortunately the inode was allocated with new_inode_pseudo instead of new_inode so the inode was not on the sb->s_inodes list. Which prevented fsnotify_unmount_inodes from finding the inode and removing the watch as well as made it so the "VFS: Busy inodes after unmount" warning could not find the inodes to warn about them. Make all of the inodes in proc visible to generic_shutdown_super, and fsnotify_sb_delete by using new_inode instead of new_inode_pseudo. The only functional difference is that new_inode places the inodes on the sb->s_inodes list. I wrote a small test program and I can verify that without changes it can trigger this issue, and by replacing new_inode_pseudo with new_inode the issues goes away. Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/000000000000d788c905a7dfa3f4@google.com Reported-by: syzbot+7d2debdcdb3cb93c1e5e@syzkaller.appspotmail.com Fixes: 0097875bd415 ("proc: Implement /proc/thread-self to point at the directory of the current thread") Fixes: 021ada7dff22 ("procfs: switch /proc/self away from proc_dir_entry") Fixes: 51f0885e5415 ("vfs,proc: guarantee unique inodes in /proc") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ef1548adada51a2f32ed7faef50aa465e1b4c5da upstream.

Recently syzbot reported that unmounting proc when there is an ongoing
inotify watch on the root directory of proc could result in a use
after free when the watch is removed after the unmount of proc
when the watcher exits.

Commit 69879c01a0c3 ("proc: Remove the now unnecessary internal mount
of proc") made it easier to unmount proc and allowed syzbot to see the
problem, but looking at the code it has been around for a long time.

Looking at the code the fsnotify watch should have been removed by
fsnotify_sb_delete in generic_shutdown_super.  Unfortunately the inode
was allocated with new_inode_pseudo instead of new_inode so the inode
was not on the sb->s_inodes list.  Which prevented
fsnotify_unmount_inodes from finding the inode and removing the watch
as well as made it so the "VFS: Busy inodes after unmount" warning
could not find the inodes to warn about them.

Make all of the inodes in proc visible to generic_shutdown_super,
and fsnotify_sb_delete by using new_inode instead of new_inode_pseudo.
The only functional difference is that new_inode places the inodes
on the sb->s_inodes list.

I wrote a small test program and I can verify that without changes it
can trigger this issue, and by replacing new_inode_pseudo with
new_inode the issues goes away.

Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/000000000000d788c905a7dfa3f4@google.com
Reported-by: syzbot+7d2debdcdb3cb93c1e5e@syzkaller.appspotmail.com
Fixes: 0097875bd415 ("proc: Implement /proc/thread-self to point at the directory of the current thread")
Fixes: 021ada7dff22 ("procfs: switch /proc/self away from proc_dir_entry")
Fixes: 51f0885e5415 ("vfs,proc: guarantee unique inodes in /proc")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29T14:31:27+00:00 Jann Horn jannh@google.com 2020-04-21T01:14:11+00:00 d8da38eafa38b03c741aa63f688e5a77343a77be commit bdebd6a2831b6fab69eb85cee74a8ba77f1a1cc2 upstream. remap_vmalloc_range() has had various issues with the bounds checks it promises to perform ("This function checks that addr is a valid vmalloc'ed area, and that it is big enough to cover the vma") over time, e.g.: - not detecting pgoff<<PAGE_SHIFT overflow - not detecting (pgoff<<PAGE_SHIFT)+usize overflow - not checking whether addr and addr+(pgoff<<PAGE_SHIFT) are the same vmalloc allocation - comparing a potentially wildly out-of-bounds pointer with the end of the vmalloc region In particular, since commit fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY"), unprivileged users can cause kernel null pointer dereferences by calling mmap() on a BPF map with a size that is bigger than the distance from the start of the BPF map to the end of the address space. This could theoretically be used as a kernel ASLR bypass, by using whether mmap() with a given offset oopses or returns an error code to perform a binary search over the possible address range. To allow remap_vmalloc_range_partial() to verify that addr and addr+(pgoff<<PAGE_SHIFT) are in the same vmalloc region, pass the offset to remap_vmalloc_range_partial() instead of adding it to the pointer in remap_vmalloc_range(). In remap_vmalloc_range_partial(), fix the check against get_vm_area_size() by using size comparisons instead of pointer comparisons, and add checks for pgoff. Fixes: 833423143c3a ("[PATCH] mm: introduce remap_vmalloc_range()") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: stable@vger.kernel.org Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Song Liu <songliubraving@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Andrii Nakryiko <andriin@fb.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@chromium.org> Link: http://lkml.kernel.org/r/20200415222312.236431-1-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bdebd6a2831b6fab69eb85cee74a8ba77f1a1cc2 upstream.

remap_vmalloc_range() has had various issues with the bounds checks it
promises to perform ("This function checks that addr is a valid
vmalloc'ed area, and that it is big enough to cover the vma") over time,
e.g.:

 - not detecting pgoff<<PAGE_SHIFT overflow

 - not detecting (pgoff<<PAGE_SHIFT)+usize overflow

 - not checking whether addr and addr+(pgoff<<PAGE_SHIFT) are the same
   vmalloc allocation

 - comparing a potentially wildly out-of-bounds pointer with the end of
   the vmalloc region

In particular, since commit fc9702273e2e ("bpf: Add mmap() support for
BPF_MAP_TYPE_ARRAY"), unprivileged users can cause kernel null pointer
dereferences by calling mmap() on a BPF map with a size that is bigger
than the distance from the start of the BPF map to the end of the
address space.

This could theoretically be used as a kernel ASLR bypass, by using
whether mmap() with a given offset oopses or returns an error code to
perform a binary search over the possible address range.

To allow remap_vmalloc_range_partial() to verify that addr and
addr+(pgoff<<PAGE_SHIFT) are in the same vmalloc region, pass the offset
to remap_vmalloc_range_partial() instead of adding it to the pointer in
remap_vmalloc_range().

In remap_vmalloc_range_partial(), fix the check against
get_vm_area_size() by using size comparisons instead of pointer
comparisons, and add checks for pgoff.

Fixes: 833423143c3a ("[PATCH] mm: introduce remap_vmalloc_range()")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Link: http://lkml.kernel.org/r/20200415222312.236431-1-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm, thp, proc: report THP eligibility for each vma 2019-12-17T19:35:45+00:00 Michal Hocko mhocko@suse.com 2018-12-28T08:38:21+00:00 c76adee3471f7fe0553904be7ab13c33eda64a19 [ Upstream commit 7635d9cbe8327e131a1d3d8517dc186c2796ce2e ] Userspace falls short when trying to find out whether a specific memory range is eligible for THP. There are usecases that would like to know that http://lkml.kernel.org/r/alpine.DEB.2.21.1809251248450.50347@chino.kir.corp.google.com : This is used to identify heap mappings that should be able to fault thp : but do not, and they normally point to a low-on-memory or fragmentation : issue. The only way to deduce this now is to query for hg resp. nh flags and confronting the state with the global setting. Except that there is also PR_SET_THP_DISABLE that might change the picture. So the final logic is not trivial. Moreover the eligibility of the vma depends on the type of VMA as well. In the past we have supported only anononymous memory VMAs but things have changed and shmem based vmas are supported as well these days and the query logic gets even more complicated because the eligibility depends on the mount option and another global configuration knob. Simplify the current state and report the THP eligibility in /proc/<pid>/smaps for each existing vma. Reuse transparent_hugepage_enabled for this purpose. The original implementation of this function assumes that the caller knows that the vma itself is supported for THP so make the core checks into __transparent_hugepage_enabled and use it for existing callers. __show_smap just use the new transparent_hugepage_enabled which also checks the vma support status (please note that this one has to be out of line due to include dependency issues). [mhocko@kernel.org: fix oops with NULL ->f_mapping] Link: http://lkml.kernel.org/r/20181224185106.GC16738@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20181211143641.3503-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Paul Oppenheimer <bepvte@gmail.com> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 7635d9cbe8327e131a1d3d8517dc186c2796ce2e ]

Userspace falls short when trying to find out whether a specific memory
range is eligible for THP.  There are usecases that would like to know
that
http://lkml.kernel.org/r/alpine.DEB.2.21.1809251248450.50347@chino.kir.corp.google.com
: This is used to identify heap mappings that should be able to fault thp
: but do not, and they normally point to a low-on-memory or fragmentation
: issue.

The only way to deduce this now is to query for hg resp.  nh flags and
confronting the state with the global setting.  Except that there is also
PR_SET_THP_DISABLE that might change the picture.  So the final logic is
not trivial.  Moreover the eligibility of the vma depends on the type of
VMA as well.  In the past we have supported only anononymous memory VMAs
but things have changed and shmem based vmas are supported as well these
days and the query logic gets even more complicated because the
eligibility depends on the mount option and another global configuration
knob.

Simplify the current state and report the THP eligibility in
/proc/<pid>/smaps for each existing vma.  Reuse
transparent_hugepage_enabled for this purpose.  The original
implementation of this function assumes that the caller knows that the vma
itself is supported for THP so make the core checks into
__transparent_hugepage_enabled and use it for existing callers.
__show_smap just use the new transparent_hugepage_enabled which also
checks the vma support status (please note that this one has to be out of
line due to include dependency issues).

[mhocko@kernel.org: fix oops with NULL ->f_mapping]
  Link: http://lkml.kernel.org/r/20181224185106.GC16738@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20181211143641.3503-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Paul Oppenheimer <bepvte@gmail.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
proc/vmcore: Fix i386 build error of missing copy_oldmem_page_encrypted() 2019-11-24T07:20:45+00:00 Borislav Petkov bp@suse.de 2018-10-08T08:05:20+00:00 94764e3ae569573903af9ea8201073eb96cb4d64 [ Upstream commit cf089611f4c446285046fcd426d90c18f37d2905 ] Lianbo reported a build error with a particular 32-bit config, see Link below for details. Provide a weak copy_oldmem_page_encrypted() function which architectures can override, in the same manner other functionality in that file is supplied. Reported-by: Lianbo Jiang <lijiang@redhat.com> Signed-off-by: Borislav Petkov <bp@suse.de> CC: x86@kernel.org Link: http://lkml.kernel.org/r/710b9d95-2f70-eadf-c4a1-c3dc80ee4ebb@redhat.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit cf089611f4c446285046fcd426d90c18f37d2905 ]

Lianbo reported a build error with a particular 32-bit config, see Link
below for details.

Provide a weak copy_oldmem_page_encrypted() function which architectures
can override, in the same manner other functionality in that file is
supplied.

Reported-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
CC: x86@kernel.org
Link: http://lkml.kernel.org/r/710b9d95-2f70-eadf-c4a1-c3dc80ee4ebb@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
fs/proc/page.c: don't access uninitialized memmaps in fs/proc/page.c 2019-10-29T08:19:56+00:00 David Hildenbrand david@redhat.com 2019-10-19T03:19:20+00:00 6ea856efef9f5c5a1a8e558ce67f72b37e2cd2a9 commit aad5f69bc161af489dbb5934868bd347282f0764 upstream. There are three places where we access uninitialized memmaps, namely: - /proc/kpagecount - /proc/kpageflags - /proc/kpagecgroup We have initialized memmaps either when the section is online or when the page was initialized to the ZONE_DEVICE. Uninitialized memmaps contain garbage and in the worst case trigger kernel BUGs, especially with CONFIG_PAGE_POISONING. For example, not onlining a DIMM during boot and calling /proc/kpagecount with CONFIG_PAGE_POISONING: :/# cat /proc/kpagecount > tmp.test BUG: unable to handle page fault for address: fffffffffffffffe #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 114616067 P4D 114616067 PUD 114618067 PMD 0 Oops: 0000 [#1] SMP NOPTI CPU: 0 PID: 469 Comm: cat Not tainted 5.4.0-rc1-next-20191004+ #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.4 RIP: 0010:kpagecount_read+0xce/0x1e0 Code: e8 09 83 e0 3f 48 0f a3 02 73 2d 4c 89 e7 48 c1 e7 06 48 03 3d ab 51 01 01 74 1d 48 8b 57 08 480 RSP: 0018:ffffa14e409b7e78 EFLAGS: 00010202 RAX: fffffffffffffffe RBX: 0000000000020000 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 00007f76b5595000 RDI: fffff35645000000 RBP: 00007f76b5595000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000140000 R13: 0000000000020000 R14: 00007f76b5595000 R15: ffffa14e409b7f08 FS: 00007f76b577d580(0000) GS:ffff8f41bd400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffffffe CR3: 0000000078960000 CR4: 00000000000006f0 Call Trace: proc_reg_read+0x3c/0x60 vfs_read+0xc5/0x180 ksys_read+0x68/0xe0 do_syscall_64+0x5c/0xa0 entry_SYSCALL_64_after_hwframe+0x49/0xbe For now, let's drop support for ZONE_DEVICE from the three pseudo files in order to fix this. To distinguish offline memory (with garbage memmap) from ZONE_DEVICE memory with properly initialized memmaps, we would have to check get_dev_pagemap() and pfn_zone_device_reserved() right now. The usage of both (especially, special casing devmem) is frowned upon and needs to be reworked. The fundamental issue we have is: if (pfn_to_online_page(pfn)) { /* memmap initialized */ } else if (pfn_valid(pfn)) { /* * ??? * a) offline memory. memmap garbage. * b) devmem: memmap initialized to ZONE_DEVICE. * c) devmem: reserved for driver. memmap garbage. * (d) devmem: memmap currently initializing - garbage) */ } We'll leave the pfn_zone_device_reserved() check in stable_page_flags() in place as that function is also used from memory failure. We now no longer dump information about pages that are not in use anymore - offline. Link: http://lkml.kernel.org/r/20191009142435.3975-2-david@redhat.com Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b319] Signed-off-by: David Hildenbrand <david@redhat.com> Reported-by: Qian Cai <cai@lca.pw> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Toshiki Fukasawa <t-fukasawa@vx.jp.nec.com> Cc: Pankaj gupta <pagupta@redhat.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Anthony Yznaga <anthony.yznaga@oracle.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: <stable@vger.kernel.org> [4.13+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit aad5f69bc161af489dbb5934868bd347282f0764 upstream.

There are three places where we access uninitialized memmaps, namely:
- /proc/kpagecount
- /proc/kpageflags
- /proc/kpagecgroup

We have initialized memmaps either when the section is online or when the
page was initialized to the ZONE_DEVICE.  Uninitialized memmaps contain
garbage and in the worst case trigger kernel BUGs, especially with
CONFIG_PAGE_POISONING.

For example, not onlining a DIMM during boot and calling /proc/kpagecount
with CONFIG_PAGE_POISONING:

  :/# cat /proc/kpagecount > tmp.test
  BUG: unable to handle page fault for address: fffffffffffffffe
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 114616067 P4D 114616067 PUD 114618067 PMD 0
  Oops: 0000 [#1] SMP NOPTI
  CPU: 0 PID: 469 Comm: cat Not tainted 5.4.0-rc1-next-20191004+ #11
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.4
  RIP: 0010:kpagecount_read+0xce/0x1e0
  Code: e8 09 83 e0 3f 48 0f a3 02 73 2d 4c 89 e7 48 c1 e7 06 48 03 3d ab 51 01 01 74 1d 48 8b 57 08 480
  RSP: 0018:ffffa14e409b7e78 EFLAGS: 00010202
  RAX: fffffffffffffffe RBX: 0000000000020000 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: 00007f76b5595000 RDI: fffff35645000000
  RBP: 00007f76b5595000 R08: 0000000000000001 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000140000
  R13: 0000000000020000 R14: 00007f76b5595000 R15: ffffa14e409b7f08
  FS:  00007f76b577d580(0000) GS:ffff8f41bd400000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: fffffffffffffffe CR3: 0000000078960000 CR4: 00000000000006f0
  Call Trace:
   proc_reg_read+0x3c/0x60
   vfs_read+0xc5/0x180
   ksys_read+0x68/0xe0
   do_syscall_64+0x5c/0xa0
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

For now, let's drop support for ZONE_DEVICE from the three pseudo files
in order to fix this.  To distinguish offline memory (with garbage
memmap) from ZONE_DEVICE memory with properly initialized memmaps, we
would have to check get_dev_pagemap() and pfn_zone_device_reserved()
right now.  The usage of both (especially, special casing devmem) is
frowned upon and needs to be reworked.

The fundamental issue we have is:

	if (pfn_to_online_page(pfn)) {
		/* memmap initialized */
	} else if (pfn_valid(pfn)) {
		/*
		 * ???
		 * a) offline memory. memmap garbage.
		 * b) devmem: memmap initialized to ZONE_DEVICE.
		 * c) devmem: reserved for driver. memmap garbage.
		 * (d) devmem: memmap currently initializing - garbage)
		 */
	}

We'll leave the pfn_zone_device_reserved() check in stable_page_flags()
in place as that function is also used from memory failure.  We now no
longer dump information about pages that are not in use anymore -
offline.

Link: http://lkml.kernel.org/r/20191009142435.3975-2-david@redhat.com
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online")	[visible after d0dc12e86b319]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Toshiki Fukasawa <t-fukasawa@vx.jp.nec.com>
Cc: Pankaj gupta <pagupta@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: <stable@vger.kernel.org>	[4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
/proc/<pid>/cmdline: add back the setproctitle() special case 2019-08-04T07:30:56+00:00 Linus Torvalds torvalds@linux-foundation.org 2019-07-13T21:27:14+00:00 54695343b4910a3a6e09513a3231336ede39484a commit d26d0cd97c88eb1a5704b42e41ab443406807810 upstream. This makes the setproctitle() special case very explicit indeed, and handles it with a separate helper function entirely. In the process, it re-instates the original semantics of simply stopping at the first NUL character when the original last NUL character is no longer there. [ The original semantics can still be seen in mm/util.c: get_cmdline() that is limited to a fixed-size buffer ] This makes the logic about when we use the string lengths etc much more obvious, and makes it easier to see what we do and what the two very different cases are. Note that even when we allow walking past the end of the argument array (because the setproctitle() might have overwritten and overflowed the original argv[] strings), we only allow it when it overflows into the environment region if it is immediately adjacent. [ Fixed for missing 'count' checks noted by Alexey Izbyshev ] Link: https://lore.kernel.org/lkml/alpine.LNX.2.21.1904052326230.3249@kich.toxcorp.com/ Fixes: 5ab827189965 ("fs/proc: simplify and clarify get_mm_cmdline() function") Cc: Jakub Jankowski <shasta@toxcorp.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Alexey Izbyshev <izbyshev@ispras.ru> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d26d0cd97c88eb1a5704b42e41ab443406807810 upstream.

This makes the setproctitle() special case very explicit indeed, and
handles it with a separate helper function entirely.  In the process, it
re-instates the original semantics of simply stopping at the first NUL
character when the original last NUL character is no longer there.

[ The original semantics can still be seen in mm/util.c: get_cmdline()
  that is limited to a fixed-size buffer ]

This makes the logic about when we use the string lengths etc much more
obvious, and makes it easier to see what we do and what the two very
different cases are.

Note that even when we allow walking past the end of the argument array
(because the setproctitle() might have overwritten and overflowed the
original argv[] strings), we only allow it when it overflows into the
environment region if it is immediately adjacent.

[ Fixed for missing 'count' checks noted by Alexey Izbyshev ]

Link: https://lore.kernel.org/lkml/alpine.LNX.2.21.1904052326230.3249@kich.toxcorp.com/
Fixes: 5ab827189965 ("fs/proc: simplify and clarify get_mm_cmdline() function")
Cc: Jakub Jankowski <shasta@toxcorp.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alexey Izbyshev <izbyshev@ispras.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
/proc/<pid>/cmdline: remove all the special cases 2019-08-04T07:30:56+00:00 Linus Torvalds torvalds@linux-foundation.org 2019-07-13T20:40:13+00:00 54ffaa53e785ad72df597bf0544b65f0dfd19cdc commit 3d712546d8ba9f25cdf080d79f90482aa4231ed4 upstream. Start off with a clean slate that only reads exactly from arg_start to arg_end, without any oddities. This simplifies the code and in the process removes the case that caused us to potentially leak an uninitialized byte from the temporary kernel buffer. Note that in order to start from scratch with an understandable base, this simplifies things _too_ much, and removes all the legacy logic to handle setproctitle() having changed the argument strings. We'll add back those special cases very differently in the next commit. Link: https://lore.kernel.org/lkml/20190712160913.17727-1-izbyshev@ispras.ru/ Fixes: f5b65348fd77 ("proc: fix missing final NUL in get_mm_cmdline() rewrite") Cc: Alexey Izbyshev <izbyshev@ispras.ru> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3d712546d8ba9f25cdf080d79f90482aa4231ed4 upstream.

Start off with a clean slate that only reads exactly from arg_start to
arg_end, without any oddities.  This simplifies the code and in the
process removes the case that caused us to potentially leak an
uninitialized byte from the temporary kernel buffer.

Note that in order to start from scratch with an understandable base,
this simplifies things _too_ much, and removes all the legacy logic to
handle setproctitle() having changed the argument strings.

We'll add back those special cases very differently in the next commit.

Link: https://lore.kernel.org/lkml/20190712160913.17727-1-izbyshev@ispras.ru/
Fixes: f5b65348fd77 ("proc: fix missing final NUL in get_mm_cmdline() rewrite")
Cc: Alexey Izbyshev <izbyshev@ispras.ru>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
proc: use down_read_killable mmap_sem for /proc/pid/maps 2019-07-31T05:27:09+00:00 Konstantin Khlebnikov khlebnikov@yandex-team.ru 2019-07-12T03:59:50+00:00 af0883f9dcf6603ca8d1a59d4baf930b7f90eeae [ Upstream commit 8a713e7df3352b8d9392476e9cf29e4e185dac32 ] Do not remain stuck forever if something goes wrong. Using a killable lock permits cleanup of stuck tasks and simplifies investigation. This function is also used for /proc/pid/smaps. Link: http://lkml.kernel.org/r/156007493160.3335.14447544314127417266.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 8a713e7df3352b8d9392476e9cf29e4e185dac32 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

This function is also used for /proc/pid/smaps.

Link: http://lkml.kernel.org/r/156007493160.3335.14447544314127417266.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
proc: use down_read_killable mmap_sem for /proc/pid/map_files 2019-07-31T05:27:09+00:00 Konstantin Khlebnikov khlebnikov@yandex-team.ru 2019-07-12T04:00:03+00:00 6ecdcbcd309167884a5672e76d35bfb02595e046 [ Upstream commit cd9e2bb8271c971d9f37c722be2616c7f8ba0664 ] Do not remain stuck forever if something goes wrong. Using a killable lock permits cleanup of stuck tasks and simplifies investigation. It seems ->d_revalidate() could return any error (except ECHILD) to abort validation and pass error as result of lookup sequence. [akpm@linux-foundation.org: fix proc_map_files_lookup() return value, per Andrei] Link: http://lkml.kernel.org/r/156007493995.3335.9595044802115356911.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit cd9e2bb8271c971d9f37c722be2616c7f8ba0664 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

It seems ->d_revalidate() could return any error (except ECHILD) to abort
validation and pass error as result of lookup sequence.

[akpm@linux-foundation.org: fix proc_map_files_lookup() return value, per Andrei]
Link: http://lkml.kernel.org/r/156007493995.3335.9595044802115356911.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
proc: use down_read_killable mmap_sem for /proc/pid/clear_refs 2019-07-31T05:27:09+00:00 Konstantin Khlebnikov khlebnikov@yandex-team.ru 2019-07-12T04:00:00+00:00 3d617da8a9567da93dde8c5a5a998b6346e1d2a0 [ Upstream commit c46038017fbdcac627b670c9d4176f1d0c2f5fa3 ] Do not remain stuck forever if something goes wrong. Using a killable lock permits cleanup of stuck tasks and simplifies investigation. Replace the only unkillable mmap_sem lock in clear_refs_write(). Link: http://lkml.kernel.org/r/156007493826.3335.5424884725467456239.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit c46038017fbdcac627b670c9d4176f1d0c2f5fa3 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Replace the only unkillable mmap_sem lock in clear_refs_write().

Link: http://lkml.kernel.org/r/156007493826.3335.5424884725467456239.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>