CVE-2023-53447: In the Linux kernel, the following vulnerability has been resolved: f2fs: don't reset unchangable mount option in f2fs_remount() syzbot reports a bug as below…

PriorityP418medium4.7CVSS 3.1

AVLACHPRLUINSUCNINAH

EPSS

0.09%

0.4th percentile

In the Linux kernel, the following vulnerability has been resolved: f2fs: don't reset unchangable mount option in f2fs_remount() syzbot reports a bug as below: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN RIP: 0010:__lock_acquire+0x69/0x2000 kernel/locking/lockdep.c:4942 Call Trace: lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691 __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline] _raw_write_lock+0x2e/0x40 kernel/locking/spinlock.c:300 __drop_extent_tree+0x3ac/0x660 fs/f2fs/extent_cache.c:1100 f2fs_drop_extent_tree+0x17/0x30 fs/f2fs/extent_cache.c:1116 f2fs_insert_range+0x2d5/0x3c0 fs/f2fs/file.c:1664 f2fs_fallocate+0x4e4/0x6d0 fs/f2fs/file.c:1838 vfs_fallocate+0x54b/0x6b0 fs/open.c:324 ksys_fallocate fs/open.c:347 [inline] __do_sys_fallocate fs/open.c:355 [inline] __se_sys_fallocate fs/open.c:353 [inline] __x64_sys_fallocate+0xbd/0x100 fs/open.c:353 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The root cause is race condition as below: - since it tries to remount rw filesystem, so that do_remount won't call sb_prepare_remount_readonly to block fallocate, there may be race condition in between remount and fallocate. - in f2fs_remount(), default_options() will reset mount option to default one, and then update it based on result of parse_options(), so there is a hole which race condition can happen. Thread A Thread B - f2fs_fill_super - parse_options - clear_opt(READ_EXTENT_CACHE) - f2fs_remount - default_options - set_opt(READ_EXTENT_CACHE) - f2fs_fallocate - f2fs_insert_range - f2fs_drop_extent_tree - __drop_extent_tree - __may_extent_tree - test_opt(READ_EXTENT_CACHE) return true - write_lock(&et->lock) access NULL pointer - parse_options - clear_opt(READ_EXTENT_CACHE)

Affected

8 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 6.4.11-1 (forky)	linux 6.4.11-1 (forky)
linux	linux	—	—
linux	linux	>= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 < 115557cc226a927924f2d7d1980ccbf6e3b3bb36	115557cc226a927924f2d7d1980ccbf6e3b3bb36
linux	linux	>= 98e4da8ca301e062d79ae168c67e56f3c3de3ce4 < 458c15dfbce62c35fefd9ca637b20a051309c9f1	458c15dfbce62c35fefd9ca637b20a051309c9f1
linux	linux_kernel	>= 0 < 6.4.11-1	6.4.11-1
linux	linux_kernel	>= 0 < 6.4.11-1	6.4.11-1
linux	linux_kernel	>= 3.8 < 6.4.5	6.4.5
msrc	cbl2_kernel_5.15.186.1-1_on_cbl_mariner_2.0	—	—

CVSS provenance

nvdv3.14.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

osv4.7MEDIUM

vendor_debian4.7MEDIUM

vendor_msrc4.7MEDIUM

vendor_redhat4.7MEDIUM

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