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| author | Denis Arefev <arefev@swemel.ru> | 2026-05-21 10:28:56 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-07-04 13:44:19 +0200 |
| commit | 3804e6de30ae7b053d53341d9d6944356cf23b40 (patch) | |
| tree | d2fa1392b3d4d28a95b89fbb1c1e6be38fcbec89 | |
| parent | db2c5b9fb908715cab9976ee5966c8493ead34bd (diff) | |
| download | linux-stable-3804e6de30ae7b053d53341d9d6944356cf23b40.tar.gz linux-stable-3804e6de30ae7b053d53341d9d6944356cf23b40.zip | |
block: Avoid mounting the bdev pseudo-filesystem in userspace
commit f73aa66dffcb8e61e78f01b56163ec16a15d06d2 upstream.
The bdev pseudo-filesystem is an internal kernel filesystem with which
userspace should not interfere. Unregister it so that userspace cannot
even attempt to mount it.
This fixes a bug [1] that occurs when attempting to access files,
because the system call move_mount() uses pointers declared in the
inode_operations structure, which for the bdev pseudo-filesystem
are always equal to 0. `inode->i_op = &empty_iops;`
[1]
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 23380067 P4D 23380067 PUD 23381067 PMD 0
Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI
CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:0x0
Call Trace:
<TASK>
lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460
open_last_lookups fs/namei.c:3550 [inline]
path_openat+0x953/0x2700 fs/namei.c:3780
do_filp_open+0x1c5/0x410 fs/namei.c:3810
do_sys_openat2+0x171/0x4d0 fs/open.c:1318
do_sys_open fs/open.c:1334 [inline]
__do_sys_openat fs/open.c:1350 [inline]
__se_sys_openat fs/open.c:1345 [inline]
__x64_sys_openat+0x13c/0x1f0 fs/open.c:1345
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Link: https://lore.kernel.org/all/20131010004732.GJ13318@ZenIV.linux.org.uk/T/#
Cc: stable@vger.kernel.org
Signed-off-by: Denis Arefev <arefev@swemel.ru>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260521072857.5078-1-arefev@swemel.ru
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | block/bdev.c | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/block/bdev.c b/block/bdev.c index 638f0cd458ae..57e78692084b 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -438,15 +438,10 @@ EXPORT_SYMBOL_GPL(blockdev_superblock); void __init bdev_cache_init(void) { - int err; - bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| SLAB_ACCOUNT|SLAB_PANIC), init_once); - err = register_filesystem(&bd_type); - if (err) - panic("Cannot register bdev pseudo-fs"); blockdev_mnt = kern_mount(&bd_type); if (IS_ERR(blockdev_mnt)) panic("Cannot create bdev pseudo-fs"); |