6.12-stable review patch. If anyone has any objections, please let me know.
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From: Vasiliy Kovalev kovalev@altlinux.org
[ Upstream commit 37bfb464ddca87f203071b5bd562cd91ddc0b40a ]
Validate db_agheight, db_agwidth, 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:
- agheight: 0 to L2LPERCTL/2 (0 to 5) ensures shift (L2LPERCTL - 2*agheight) >= 0. - agwidth: 1 to min(LPERCTL/MAXAG, 2^(L2LPERCTL - 2*agheight)) ensures agperlev >= 1. - Ranges: 1-8 (agheight 0-3), 1-4 (agheight 4), 1 (agheight 5). - LPERCTL/MAXAG = 1024/128 = 8 limits leaves per AG; 2^(10 - 2*agheight) prevents division to 0. - agstart: 0 to CTLTREESIZE-1 - agwidth*(MAXAG-1) keeps ti within stree (size 1365). - Ranges: 0-1237 (agwidth 1), 0-348 (agwidth 8).
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.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> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 ubsan_epilogue lib/ubsan.c:231 [inline] __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468 dbAllocAG+0x1087/0x10b0 fs/jfs/jfs_dmap.c:1400 dbDiscardAG+0x352/0xa20 fs/jfs/jfs_dmap.c:1613 jfs_ioc_trim+0x45a/0x6b0 fs/jfs/jfs_discard.c:105 jfs_ioctl+0x2cd/0x3e0 fs/jfs/ioctl.c:131 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892 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
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Cc: stable@vger.kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+fe8264911355151c487f@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=fe8264911355151c487f Signed-off-by: Vasiliy Kovalev kovalev@altlinux.org Signed-off-by: Dave Kleikamp dave.kleikamp@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/jfs/jfs_dmap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index 26e89d0c69b61..35e063c9f3a42 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -194,7 +194,11 @@ int dbMount(struct inode *ipbmap) !bmp->db_numag || (bmp->db_numag > MAXAG) || (bmp->db_maxag >= MAXAG) || (bmp->db_maxag < 0) || (bmp->db_agpref >= MAXAG) || (bmp->db_agpref < 0) || - !bmp->db_agwidth || + (bmp->db_agheight < 0) || (bmp->db_agheight > (L2LPERCTL >> 1)) || + (bmp->db_agwidth < 1) || (bmp->db_agwidth > (LPERCTL / MAXAG)) || + (bmp->db_agwidth > (1 << (L2LPERCTL - (bmp->db_agheight << 1)))) || + (bmp->db_agstart < 0) || + (bmp->db_agstart > (CTLTREESIZE - 1 - bmp->db_agwidth * (MAXAG - 1))) || (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG) || (bmp->db_agl2size < 0) || ((bmp->db_mapsize - 1) >> bmp->db_agl2size) > MAXAG) {