linux-stable.git/fs, branch v5.4.263 Linux kernel stable tree ovl: skip overlayfs superblocks at global sync 2023-12-08T07:44:27+00:00 Konstantin Khlebnikov khlebnikov@yandex-team.ru 2020-04-09T08:29:47+00:00 8c85e455f7c9682d2728e64aaaf36b8c490dfce3 [ Upstream commit 32b1924b210a70dcacdf65abd687c5ef86a67541 ] Stacked filesystems like overlayfs has no own writeback, but they have to forward syncfs() requests to backend for keeping data integrity. During global sync() each overlayfs instance calls method ->sync_fs() for backend although it itself is in global list of superblocks too. As a result one syscall sync() could write one superblock several times and send multiple disk barriers. This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that. Reported-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Stable-dep-of: b836c4d29f27 ("ima: detect changes to the backing overlay file") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 32b1924b210a70dcacdf65abd687c5ef86a67541 ]

Stacked filesystems like overlayfs has no own writeback, but they have to
forward syncfs() requests to backend for keeping data integrity.

During global sync() each overlayfs instance calls method ->sync_fs() for
backend although it itself is in global list of superblocks too.  As a
result one syscall sync() could write one superblock several times and send
multiple disk barriers.

This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that.

Reported-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Stable-dep-of: b836c4d29f27 ("ima: detect changes to the backing overlay file")
Signed-off-by: Sasha Levin <sashal@kernel.org>
smb3: fix touch -h of symlink 2023-12-08T07:44:27+00:00 Steve French stfrench@microsoft.com 2023-10-16T17:18:23+00:00 f1db39b1541fe4c85f3250dbbd9b2d667c3bb4c7 [ Upstream commit 475efd9808a3094944a56240b2711349e433fb66 ] For example: touch -h -t 02011200 testfile where testfile is a symlink would not change the timestamp, but touch -t 02011200 testfile does work to change the timestamp of the target Suggested-by: David Howells <dhowells@redhat.com> Reported-by: Micah Veilleux <micah.veilleux@iba-group.com> Closes: https://bugzilla.samba.org/show_bug.cgi?id=14476 Cc: stable@vger.kernel.org Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 475efd9808a3094944a56240b2711349e433fb66 ]

For example:
      touch -h -t 02011200 testfile
where testfile is a symlink would not change the timestamp, but
      touch -t 02011200 testfile
does work to change the timestamp of the target

Suggested-by: David Howells <dhowells@redhat.com>
Reported-by: Micah Veilleux <micah.veilleux@iba-group.com>
Closes: https://bugzilla.samba.org/show_bug.cgi?id=14476
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
btrfs: make error messages more clear when getting a chunk map 2023-12-08T07:44:26+00:00 Filipe Manana fdmanana@suse.com 2023-11-21T13:38:33+00:00 6536698eea9156fbc36f621152db597db006871a commit 7d410d5efe04e42a6cd959bfe6d59d559fdf8b25 upstream. When getting a chunk map, at btrfs_get_chunk_map(), we do some sanity checks to verify we found a chunk map and that map found covers the logical address the caller passed in. However the messages aren't very clear in the sense that don't mention the issue is with a chunk map and one of them prints the 'length' argument as if it were the end offset of the requested range (while the in the string format we use %llu-%llu which suggests a range, and the second %llu-%llu is actually a range for the chunk map). So improve these two details in the error messages. CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 7d410d5efe04e42a6cd959bfe6d59d559fdf8b25 upstream.

When getting a chunk map, at btrfs_get_chunk_map(), we do some sanity
checks to verify we found a chunk map and that map found covers the
logical address the caller passed in. However the messages aren't very
clear in the sense that don't mention the issue is with a chunk map and
one of them prints the 'length' argument as if it were the end offset of
the requested range (while the in the string format we use %llu-%llu
which suggests a range, and the second %llu-%llu is actually a range for
the chunk map). So improve these two details in the error messages.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
btrfs: send: ensure send_fd is writable 2023-12-08T07:44:26+00:00 Jann Horn jannh@google.com 2023-11-24T16:48:31+00:00 4c6274cfd60345b7c9526e0c4bbf557f30745ced commit 0ac1d13a55eb37d398b63e6ff6db4a09a2c9128c upstream. kernel_write() requires the caller to ensure that the file is writable. Let's do that directly after looking up the ->send_fd. We don't need a separate bailout path because the "out" path already does fput() if ->send_filp is non-NULL. This has no security impact for two reasons: - the ioctl requires CAP_SYS_ADMIN - __kernel_write() bails out on read-only files - but only since 5.8, see commit a01ac27be472 ("fs: check FMODE_WRITE in __kernel_write") Reported-and-tested-by: syzbot+12e098239d20385264d3@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=12e098239d20385264d3 Fixes: 31db9f7c23fb ("Btrfs: introduce BTRFS_IOC_SEND for btrfs send/receive") CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Jann Horn <jannh@google.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0ac1d13a55eb37d398b63e6ff6db4a09a2c9128c upstream.

kernel_write() requires the caller to ensure that the file is writable.
Let's do that directly after looking up the ->send_fd.

We don't need a separate bailout path because the "out" path already
does fput() if ->send_filp is non-NULL.

This has no security impact for two reasons:

 - the ioctl requires CAP_SYS_ADMIN
 - __kernel_write() bails out on read-only files - but only since 5.8,
   see commit a01ac27be472 ("fs: check FMODE_WRITE in __kernel_write")

Reported-and-tested-by: syzbot+12e098239d20385264d3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=12e098239d20385264d3
Fixes: 31db9f7c23fb ("Btrfs: introduce BTRFS_IOC_SEND for btrfs send/receive")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
btrfs: fix off-by-one when checking chunk map includes logical address 2023-12-08T07:44:26+00:00 Filipe Manana fdmanana@suse.com 2023-11-21T13:38:32+00:00 79ffc04aba7a58046cc4264ec5fb02b95b7a1444 commit 5fba5a571858ce2d787fdaf55814e42725bfa895 upstream. At btrfs_get_chunk_map() we get the extent map for the chunk that contains the given logical address stored in the 'logical' argument. Then we do sanity checks to verify the extent map contains the logical address. One of these checks verifies if the extent map covers a range with an end offset behind the target logical address - however this check has an off-by-one error since it will consider an extent map whose start offset plus its length matches the target logical address as inclusive, while the fact is that the last byte it covers is behind the target logical address (by 1). So fix this condition by using '<=' rather than '<' when comparing the extent map's "start + length" against the target logical address. CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5fba5a571858ce2d787fdaf55814e42725bfa895 upstream.

At btrfs_get_chunk_map() we get the extent map for the chunk that contains
the given logical address stored in the 'logical' argument. Then we do
sanity checks to verify the extent map contains the logical address. One
of these checks verifies if the extent map covers a range with an end
offset behind the target logical address - however this check has an
off-by-one error since it will consider an extent map whose start offset
plus its length matches the target logical address as inclusive, while
the fact is that the last byte it covers is behind the target logical
address (by 1).

So fix this condition by using '<=' rather than '<' when comparing the
extent map's "start + length" against the target logical address.

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
btrfs: add dmesg output for first mount and last unmount of a filesystem 2023-12-08T07:44:26+00:00 Qu Wenruo wqu@suse.com 2023-11-01T21:24:50+00:00 dd94ffab1b6d84b3ba9a8d09b6b0f44610d397eb commit 2db313205f8b96eea467691917138d646bb50aef upstream. There is a feature request to add dmesg output when unmounting a btrfs. There are several alternative methods to do the same thing, but with their own problems: - Use eBPF to watch btrfs_put_super()/open_ctree() Not end user friendly, they have to dip their head into the source code. - Watch for directory /sys/fs/<uuid>/ This is way more simple, but still requires some simple device -> uuid lookups. And a script needs to use inotify to watch /sys/fs/. Compared to all these, directly outputting the information into dmesg would be the most simple one, with both device and UUID included. And since we're here, also add the output when mounting a filesystem for the first time for parity. A more fine grained monitoring of subvolume mounts should be done by another layer, like audit. Now mounting a btrfs with all default mkfs options would look like this: [81.906566] BTRFS info (device dm-8): first mount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2 [81.907494] BTRFS info (device dm-8): using crc32c (crc32c-intel) checksum algorithm [81.908258] BTRFS info (device dm-8): using free space tree [81.912644] BTRFS info (device dm-8): auto enabling async discard [81.913277] BTRFS info (device dm-8): checking UUID tree [91.668256] BTRFS info (device dm-8): last unmount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2 CC: stable@vger.kernel.org # 5.4+ Link: https://github.com/kdave/btrfs-progs/issues/689 Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2db313205f8b96eea467691917138d646bb50aef upstream.

There is a feature request to add dmesg output when unmounting a btrfs.
There are several alternative methods to do the same thing, but with
their own problems:

- Use eBPF to watch btrfs_put_super()/open_ctree()
  Not end user friendly, they have to dip their head into the source
  code.

- Watch for directory /sys/fs/<uuid>/
  This is way more simple, but still requires some simple device -> uuid
  lookups.  And a script needs to use inotify to watch /sys/fs/.

Compared to all these, directly outputting the information into dmesg
would be the most simple one, with both device and UUID included.

And since we're here, also add the output when mounting a filesystem for
the first time for parity. A more fine grained monitoring of subvolume
mounts should be done by another layer, like audit.

Now mounting a btrfs with all default mkfs options would look like this:

  [81.906566] BTRFS info (device dm-8): first mount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2
  [81.907494] BTRFS info (device dm-8): using crc32c (crc32c-intel) checksum algorithm
  [81.908258] BTRFS info (device dm-8): using free space tree
  [81.912644] BTRFS info (device dm-8): auto enabling async discard
  [81.913277] BTRFS info (device dm-8): checking UUID tree
  [91.668256] BTRFS info (device dm-8): last unmount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2

CC: stable@vger.kernel.org # 5.4+
Link: https://github.com/kdave/btrfs-progs/issues/689
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
io_uring: fix off-by one bvec index 2023-12-08T07:44:26+00:00 Keith Busch kbusch@kernel.org 2023-11-20T22:18:31+00:00 40532b29138e9dee9997f82f13ed36c010927882 commit d6fef34ee4d102be448146f24caf96d7b4a05401 upstream. If the offset equals the bv_len of the first registered bvec, then the request does not include any of that first bvec. Skip it so that drivers don't have to deal with a zero length bvec, which was observed to break NVMe's PRP list creation. Cc: stable@vger.kernel.org Fixes: bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed buffers") Signed-off-by: Keith Busch <kbusch@kernel.org> Link: https://lore.kernel.org/r/20231120221831.2646460-1-kbusch@meta.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d6fef34ee4d102be448146f24caf96d7b4a05401 upstream.

If the offset equals the bv_len of the first registered bvec, then the
request does not include any of that first bvec. Skip it so that drivers
don't have to deal with a zero length bvec, which was observed to break
NVMe's PRP list creation.

Cc: stable@vger.kernel.org
Fixes: bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed buffers")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20231120221831.2646460-1-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ext4: make sure allocate pending entry not fail 2023-12-08T07:44:24+00:00 Zhang Yi yi.zhang@huawei.com 2023-08-24T09:26:05+00:00 32cfd5c3b8431cff5455ae1da2f7d50cffbf1da0 [ Upstream commit 8e387c89e96b9543a339f84043cf9df15fed2632 ] __insert_pending() allocate memory in atomic context, so the allocation could fail, but we are not handling that failure now. It could lead ext4_es_remove_extent() to get wrong reserved clusters, and the global data blocks reservation count will be incorrect. The same to extents_status entry preallocation, preallocate pending entry out of the i_es_lock with __GFP_NOFAIL, make sure __insert_pending() and __revise_pending() always succeeds. Signed-off-by: Zhang Yi <yi.zhang@huawei.com> Cc: stable@kernel.org Link: https://lore.kernel.org/r/20230824092619.1327976-3-yi.zhang@huaweicloud.com Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 8e387c89e96b9543a339f84043cf9df15fed2632 ]

__insert_pending() allocate memory in atomic context, so the allocation
could fail, but we are not handling that failure now. It could lead
ext4_es_remove_extent() to get wrong reserved clusters, and the global
data blocks reservation count will be incorrect. The same to
extents_status entry preallocation, preallocate pending entry out of the
i_es_lock with __GFP_NOFAIL, make sure __insert_pending() and
__revise_pending() always succeeds.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230824092619.1327976-3-yi.zhang@huaweicloud.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ext4: fix slab-use-after-free in ext4_es_insert_extent() 2023-12-08T07:44:24+00:00 Baokun Li libaokun1@huawei.com 2023-08-15T07:08:08+00:00 70edeedd795a634fdd99e757c7931b9e81686560 [ Upstream commit 768d612f79822d30a1e7d132a4d4b05337ce42ec ] Yikebaer reported an issue: ================================================================== BUG: KASAN: slab-use-after-free in ext4_es_insert_extent+0xc68/0xcb0 fs/ext4/extents_status.c:894 Read of size 4 at addr ffff888112ecc1a4 by task syz-executor/8438 CPU: 1 PID: 8438 Comm: syz-executor Not tainted 6.5.0-rc5 #1 Call Trace: [...] kasan_report+0xba/0xf0 mm/kasan/report.c:588 ext4_es_insert_extent+0xc68/0xcb0 fs/ext4/extents_status.c:894 ext4_map_blocks+0x92a/0x16f0 fs/ext4/inode.c:680 ext4_alloc_file_blocks.isra.0+0x2df/0xb70 fs/ext4/extents.c:4462 ext4_zero_range fs/ext4/extents.c:4622 [inline] ext4_fallocate+0x251c/0x3ce0 fs/ext4/extents.c:4721 [...] Allocated by task 8438: [...] kmem_cache_zalloc include/linux/slab.h:693 [inline] __es_alloc_extent fs/ext4/extents_status.c:469 [inline] ext4_es_insert_extent+0x672/0xcb0 fs/ext4/extents_status.c:873 ext4_map_blocks+0x92a/0x16f0 fs/ext4/inode.c:680 ext4_alloc_file_blocks.isra.0+0x2df/0xb70 fs/ext4/extents.c:4462 ext4_zero_range fs/ext4/extents.c:4622 [inline] ext4_fallocate+0x251c/0x3ce0 fs/ext4/extents.c:4721 [...] Freed by task 8438: [...] kmem_cache_free+0xec/0x490 mm/slub.c:3823 ext4_es_try_to_merge_right fs/ext4/extents_status.c:593 [inline] __es_insert_extent+0x9f4/0x1440 fs/ext4/extents_status.c:802 ext4_es_insert_extent+0x2ca/0xcb0 fs/ext4/extents_status.c:882 ext4_map_blocks+0x92a/0x16f0 fs/ext4/inode.c:680 ext4_alloc_file_blocks.isra.0+0x2df/0xb70 fs/ext4/extents.c:4462 ext4_zero_range fs/ext4/extents.c:4622 [inline] ext4_fallocate+0x251c/0x3ce0 fs/ext4/extents.c:4721 [...] ================================================================== The flow of issue triggering is as follows: 1. remove es raw es es removed es1 |-------------------| -> |----|.......|------| 2. insert es es insert es1 merge with es es1 merge with es and free es1 |----|.......|------| -> |------------|------| -> |-------------------| es merges with newes, then merges with es1, frees es1, then determines if es1->es_len is 0 and triggers a UAF. The code flow is as follows: ext4_es_insert_extent es1 = __es_alloc_extent(true); es2 = __es_alloc_extent(true); __es_remove_extent(inode, lblk, end, NULL, es1) __es_insert_extent(inode, &newes, es1) ---> insert es1 to es tree __es_insert_extent(inode, &newes, es2) ext4_es_try_to_merge_right ext4_es_free_extent(inode, es1) ---> es1 is freed if (es1 && !es1->es_len) // Trigger UAF by determining if es1 is used. We determine whether es1 or es2 is used immediately after calling __es_remove_extent() or __es_insert_extent() to avoid triggering a UAF if es1 or es2 is freed. Reported-by: Yikebaer Aizezi <yikebaer61@gmail.com> Closes: https://lore.kernel.org/lkml/CALcu4raD4h9coiyEBL4Bm0zjDwxC2CyPiTwsP3zFuhot6y9Beg@mail.gmail.com Fixes: 2a69c450083d ("ext4: using nofail preallocation in ext4_es_insert_extent()") Cc: stable@kernel.org Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20230815070808.3377171-1-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Stable-dep-of: 8e387c89e96b ("ext4: make sure allocate pending entry not fail") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 768d612f79822d30a1e7d132a4d4b05337ce42ec ]

Yikebaer reported an issue:
==================================================================
BUG: KASAN: slab-use-after-free in ext4_es_insert_extent+0xc68/0xcb0
fs/ext4/extents_status.c:894
Read of size 4 at addr ffff888112ecc1a4 by task syz-executor/8438

CPU: 1 PID: 8438 Comm: syz-executor Not tainted 6.5.0-rc5 #1
Call Trace:
 [...]
 kasan_report+0xba/0xf0 mm/kasan/report.c:588
 ext4_es_insert_extent+0xc68/0xcb0 fs/ext4/extents_status.c:894
 ext4_map_blocks+0x92a/0x16f0 fs/ext4/inode.c:680
 ext4_alloc_file_blocks.isra.0+0x2df/0xb70 fs/ext4/extents.c:4462
 ext4_zero_range fs/ext4/extents.c:4622 [inline]
 ext4_fallocate+0x251c/0x3ce0 fs/ext4/extents.c:4721
 [...]

Allocated by task 8438:
 [...]
 kmem_cache_zalloc include/linux/slab.h:693 [inline]
 __es_alloc_extent fs/ext4/extents_status.c:469 [inline]
 ext4_es_insert_extent+0x672/0xcb0 fs/ext4/extents_status.c:873
 ext4_map_blocks+0x92a/0x16f0 fs/ext4/inode.c:680
 ext4_alloc_file_blocks.isra.0+0x2df/0xb70 fs/ext4/extents.c:4462
 ext4_zero_range fs/ext4/extents.c:4622 [inline]
 ext4_fallocate+0x251c/0x3ce0 fs/ext4/extents.c:4721
 [...]

Freed by task 8438:
 [...]
 kmem_cache_free+0xec/0x490 mm/slub.c:3823
 ext4_es_try_to_merge_right fs/ext4/extents_status.c:593 [inline]
 __es_insert_extent+0x9f4/0x1440 fs/ext4/extents_status.c:802
 ext4_es_insert_extent+0x2ca/0xcb0 fs/ext4/extents_status.c:882
 ext4_map_blocks+0x92a/0x16f0 fs/ext4/inode.c:680
 ext4_alloc_file_blocks.isra.0+0x2df/0xb70 fs/ext4/extents.c:4462
 ext4_zero_range fs/ext4/extents.c:4622 [inline]
 ext4_fallocate+0x251c/0x3ce0 fs/ext4/extents.c:4721
 [...]
==================================================================

The flow of issue triggering is as follows:
1. remove es
      raw es               es  removed  es1
|-------------------| -> |----|.......|------|

2. insert es
  es   insert   es1      merge with es  es1     merge with es and free es1
|----|.......|------| -> |------------|------| -> |-------------------|

es merges with newes, then merges with es1, frees es1, then determines
if es1->es_len is 0 and triggers a UAF.

The code flow is as follows:
ext4_es_insert_extent
  es1 = __es_alloc_extent(true);
  es2 = __es_alloc_extent(true);
  __es_remove_extent(inode, lblk, end, NULL, es1)
    __es_insert_extent(inode, &newes, es1) ---> insert es1 to es tree
  __es_insert_extent(inode, &newes, es2)
    ext4_es_try_to_merge_right
      ext4_es_free_extent(inode, es1) --->  es1 is freed
  if (es1 && !es1->es_len)
    // Trigger UAF by determining if es1 is used.

We determine whether es1 or es2 is used immediately after calling
__es_remove_extent() or __es_insert_extent() to avoid triggering a
UAF if es1 or es2 is freed.

Reported-by: Yikebaer Aizezi <yikebaer61@gmail.com>
Closes: https://lore.kernel.org/lkml/CALcu4raD4h9coiyEBL4Bm0zjDwxC2CyPiTwsP3zFuhot6y9Beg@mail.gmail.com
Fixes: 2a69c450083d ("ext4: using nofail preallocation in ext4_es_insert_extent()")
Cc: stable@kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230815070808.3377171-1-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Stable-dep-of: 8e387c89e96b ("ext4: make sure allocate pending entry not fail")
Signed-off-by: Sasha Levin <sashal@kernel.org>
ext4: using nofail preallocation in ext4_es_insert_extent() 2023-12-08T07:44:24+00:00 Baokun Li libaokun1@huawei.com 2023-04-24T03:38:42+00:00 15a84cf4c78531224aea101c6d965b7c1cdeba01 [ Upstream commit 2a69c450083db164596c75c0f5b4d9c4c0e18eba ] Similar to in ext4_es_insert_delayed_block(), we use preallocations that do not fail to avoid inconsistencies, but we do not care about es that are not must be kept, and we return 0 even if such es memory allocation fails. Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20230424033846.4732-9-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Stable-dep-of: 8e387c89e96b ("ext4: make sure allocate pending entry not fail") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2a69c450083db164596c75c0f5b4d9c4c0e18eba ]

Similar to in ext4_es_insert_delayed_block(), we use preallocations that
do not fail to avoid inconsistencies, but we do not care about es that are
not must be kept, and we return 0 even if such es memory allocation fails.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230424033846.4732-9-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Stable-dep-of: 8e387c89e96b ("ext4: make sure allocate pending entry not fail")
Signed-off-by: Sasha Levin <sashal@kernel.org>