From: Edward Adam Davis Date: Thu, 11 Apr 2024 12:05:28 +0000 (+0800) Subject: jfs: fix null ptr deref in dtInsertEntry X-Git-Tag: v5.15.189~54 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f98bf80b20f4a930589cda48a35f751a64fe0dc2;p=thirdparty%2Fkernel%2Fstable.git jfs: fix null ptr deref in dtInsertEntry commit ce6dede912f064a855acf6f04a04cbb2c25b8c8c upstream. [syzbot reported] general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 5061 Comm: syz-executor404 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 RIP: 0010:dtInsertEntry+0xd0c/0x1780 fs/jfs/jfs_dtree.c:3713 ... [Analyze] In dtInsertEntry(), when the pointer h has the same value as p, after writing name in UniStrncpy_to_le(), p->header.flag will be cleared. This will cause the previously true judgment "p->header.flag & BT-LEAF" to change to no after writing the name operation, this leads to entering an incorrect branch and accessing the uninitialized object ih when judging this condition for the second time. [Fix] After got the page, check freelist first, if freelist == 0 then exit dtInsert() and return -EINVAL. Reported-by: syzbot+bba84aef3a26fb93deb9@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis Signed-off-by: Dave Kleikamp Signed-off-by: Aditya Dutt Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c index 27ca98614b0bb..cb57d4f1161f0 100644 --- a/fs/jfs/jfs_dtree.c +++ b/fs/jfs/jfs_dtree.c @@ -835,6 +835,8 @@ int dtInsert(tid_t tid, struct inode *ip, * the full page. */ DT_GETSEARCH(ip, btstack->top, bn, mp, p, index); + if (p->header.freelist == 0) + return -EINVAL; /* * insert entry for new key