5.4-stable review patch. If anyone has any objections, please let me know.
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From: Edward Adam Davis eadavis@qq.com
[ Upstream commit d6c1b3599b2feb5c7291f5ac3a36e5fa7cedb234 ]
[syzbot reported] ================================================================== BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/mutex.c:587 [inline] BUG: KASAN: slab-use-after-free in __mutex_lock+0xfe/0xd70 kernel/locking/mutex.c:752 Read of size 8 at addr ffff8880229254b0 by task syz-executor357/5216
CPU: 0 UID: 0 PID: 5216 Comm: syz-executor357 Not tainted 6.11.0-rc3-syzkaller-00156-gd7a5aa4b3c00 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 __mutex_lock_common kernel/locking/mutex.c:587 [inline] __mutex_lock+0xfe/0xd70 kernel/locking/mutex.c:752 dbFreeBits+0x7ea/0xd90 fs/jfs/jfs_dmap.c:2390 dbFreeDmap fs/jfs/jfs_dmap.c:2089 [inline] dbFree+0x35b/0x680 fs/jfs/jfs_dmap.c:409 dbDiscardAG+0x8a9/0xa20 fs/jfs/jfs_dmap.c:1650 jfs_ioc_trim+0x433/0x670 fs/jfs/jfs_discard.c:100 jfs_ioctl+0x2d0/0x3e0 fs/jfs/ioctl.c:131 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
Freed by task 5218: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579 poison_slab_object+0xe0/0x150 mm/kasan/common.c:240 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256 kasan_slab_free include/linux/kasan.h:184 [inline] slab_free_hook mm/slub.c:2252 [inline] slab_free mm/slub.c:4473 [inline] kfree+0x149/0x360 mm/slub.c:4594 dbUnmount+0x11d/0x190 fs/jfs/jfs_dmap.c:278 jfs_mount_rw+0x4ac/0x6a0 fs/jfs/jfs_mount.c:247 jfs_remount+0x3d1/0x6b0 fs/jfs/super.c:454 reconfigure_super+0x445/0x880 fs/super.c:1083 vfs_cmd_reconfigure fs/fsopen.c:263 [inline] vfs_fsconfig_locked fs/fsopen.c:292 [inline] __do_sys_fsconfig fs/fsopen.c:473 [inline] __se_sys_fsconfig+0xb6e/0xf80 fs/fsopen.c:345 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
[Analysis] There are two paths (dbUnmount and jfs_ioc_trim) that generate race condition when accessing bmap, which leads to the occurrence of uaf.
Use the lock s_umount to synchronize them, in order to avoid uaf caused by race condition.
Reported-and-tested-by: syzbot+3c010e21296f33a5dc16@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis eadavis@qq.com Signed-off-by: Dave Kleikamp dave.kleikamp@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/jfs/jfs_discard.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/jfs/jfs_discard.c b/fs/jfs/jfs_discard.c index 575cb2ba74fc8..5f4b305030ad5 100644 --- a/fs/jfs/jfs_discard.c +++ b/fs/jfs/jfs_discard.c @@ -65,7 +65,7 @@ void jfs_issue_discard(struct inode *ip, u64 blkno, u64 nblocks) int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range) { struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap; - struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap; + struct bmap *bmp; struct super_block *sb = ipbmap->i_sb; int agno, agno_end; u64 start, end, minlen; @@ -83,10 +83,15 @@ int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range) if (minlen == 0) minlen = 1;
+ down_read(&sb->s_umount); + bmp = JFS_SBI(ip->i_sb)->bmap; + if (minlen > bmp->db_agsize || start >= bmp->db_mapsize || - range->len < sb->s_blocksize) + range->len < sb->s_blocksize) { + up_read(&sb->s_umount); return -EINVAL; + }
if (end >= bmp->db_mapsize) end = bmp->db_mapsize - 1; @@ -100,6 +105,8 @@ int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range) trimmed += dbDiscardAG(ip, agno, minlen); agno++; } + + up_read(&sb->s_umount); range->len = trimmed << sb->s_blocksize_bits;
return 0;