Messages in this thread Patch in this message | | | From | mirimmad@outlook ... | Subject | [PATCH] FS: JFS: Fix null-ptr-deref Read in txBegin | Date | Sun, 26 Mar 2023 21:50:30 +0530 |
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From: Immad Mir <mirimmad17@gmail.com>
syzkaller reported the following issue:
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:72 [inline] BUG: KASAN: null-ptr-deref in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] BUG: KASAN: null-ptr-deref in txBegin+0x131/0x6c0 fs/jfs/jfs_txnmgr.c:366 Read of size 8 at addr 0000000000000040 by task syz-executor.0/5098
CPU: 0 PID: 5098 Comm: syz-executor.0 Not tainted 6.3.0-rc3-syzkaller-00005-g7d31677bb7b1 #0 Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_report+0xe6/0x540 mm/kasan/report.c:433 kasan_report+0x176/0x1b0 mm/kasan/report.c:536 kasan_check_range+0x283/0x290 mm/kasan/generic.c:187 instrument_atomic_read include/linux/instrumented.h:72 [inline] _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] txBegin+0x131/0x6c0 fs/jfs/jfs_txnmgr.c:366 jfs_link+0x1ac/0x5e0 fs/jfs/namei.c:802 vfs_link+0x4ed/0x680 fs/namei.c:4522 do_linkat+0x5cc/0x9e0 fs/namei.c:4593 __do_sys_linkat fs/namei.c:4621 [inline] __se_sys_linkat fs/namei.c:4618 [inline] __x64_sys_linkat+0xdd/0xf0 fs/namei.c:4618 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 issue can be resolved by checking whethere "log" for a given superblock exists in the jfs_link function before beginning a transaction.
Tested with syzbot. Reported-by: syzbot+f1faa20eec55e0c8644c@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=be7e52c50c5182cc09a09ea6fc456446b2039de3
Signed-off-by: Immad Mir <mirimmad17@gmail.com> --- fs/jfs/namei.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/jfs/namei.c b/fs/jfs/namei.c index b29d68b5e..cd43b68e2 100644 --- a/fs/jfs/namei.c +++ b/fs/jfs/namei.c @@ -799,6 +799,8 @@ static int jfs_link(struct dentry *old_dentry, if (rc) goto out;
+ if (!(JFS_SBI(ip->i_sb)->log)) + goto out; tid = txBegin(ip->i_sb, 0);
mutex_lock_nested(&JFS_IP(dir)->commit_mutex, COMMIT_MUTEX_PARENT); -- 2.40.0
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