In the Linux kernel, the following vulnerability has been resolved:
jfs: validate AG parameters in dbMount() to prevent crashes
Validate dbagheight, dbagwidth, and db_agstart in dbMount to catch corrupted metadata early and avoid undefined behavior in dbAllocAG. Limits are derived from L2LPERCTL, LPERCTL/MAXAG, and CTLTREESIZE:
UBSAN: shift-out-of-bounds in fs/jfs/jfsdmap.c:1400:9 shift exponent -335544310 is negative CPU: 0 UID: 0 PID: 5822 Comm: syz-executor130 Not tainted 6.14.0-rc5-syzkaller #0 Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: <TASK> _dumpstack lib/dumpstack.c:94 [inline] dumpstacklvl+0x241/0x360 lib/dumpstack.c:120 ubsanepilogue lib/ubsan.c:231 [inline] _ubsanhandleshiftoutofbounds+0x3c8/0x420 lib/ubsan.c:468 dbAllocAG+0x1087/0x10b0 fs/jfs/jfsdmap.c:1400 dbDiscardAG+0x352/0xa20 fs/jfs/jfsdmap.c:1613 jfsioctrim+0x45a/0x6b0 fs/jfs/jfsdiscard.c:105 jfsioctl+0x2cd/0x3e0 fs/jfs/ioctl.c:131 vfsioctl fs/ioctl.c:51 [inline] _dosysioctl fs/ioctl.c:906 [inline] _sesysioctl+0xf5/0x170 fs/ioctl.c:892 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0xf3/0x230 arch/x86/entry/common.c:83 entrySYSCALL64after_hwframe+0x77/0x7f
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.