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* [PATCH v4] jfs: UBSAN: shift-out-of-bounds in dbFindBits
  2024-10-25  6:49 syzbot
@ 2024-11-01  9:59 Matt Jan
  2024-11-01 10:20 ` [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2) syzbot
  -1 siblings, 1 reply; 6+ messages in thread
From: Matt Jan @ 2024-11-01  9:59 UTC (permalink / raw)
  To: Dave Kleikamp, jfs-discussion, linux-kernel, Shuan Khan
  Cc: Matt Jan, syzbot+9e90a1c5eedb9dc4c6cc

Ensure l2nb is less than BUDMIN by performing a sanity check in the caller.
Return -EIO if the check fails.

#syz test

Reported-by: syzbot+9e90a1c5eedb9dc4c6cc@syzkaller.appspotmail.com
Signed-off-by: Matt Jan <zoo868e@gmail.com>
---
Changes in v4: Thanks to Shaggy for the review. We now perform a sanity check instead of continuing as if nothing is wrong.
Changes in v3: Return the result earlier instead of assert it
Changes in v2: Test if the patch resolve the issue through syzbot and reference the reporter

 fs/jfs/jfs_dmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 974ecf5e0d95..89c22a18314f 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -1217,7 +1217,7 @@ dbAllocNear(struct bmap * bmp,
 	int word, lword, rc;
 	s8 *leaf;
 
-	if (dp->tree.leafidx != cpu_to_le32(LEAFIND)) {
+	if (dp->tree.leafidx != cpu_to_le32(LEAFIND) || l2nb >= L2DBWORD) {
 		jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmap page\n");
 		return -EIO;
 	}
@@ -1969,7 +1969,7 @@ dbAllocDmapLev(struct bmap * bmp,
 	if (dbFindLeaf((dmtree_t *) &dp->tree, l2nb, &leafidx, false))
 		return -ENOSPC;
 
-	if (leafidx < 0)
+	if (leafidx < 0 || l2nb >= L2DBWORD)
 		return -EIO;
 
 	/* determine the block number within the file system corresponding
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH v3] jfs: UBSAN: shift-out-of-bounds in dbFindBits
  2024-10-25  6:49 syzbot
@ 2024-10-25 17:00 Matt Jan
  2024-10-25 17:20 ` [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2) syzbot
  -1 siblings, 1 reply; 6+ messages in thread
From: Matt Jan @ 2024-10-25 17:00 UTC (permalink / raw)
  To: Dave Kleikamp, jfs-discussion, linux-kernel, Shuah Khan
  Cc: Matt Jan, syzbot+9e90a1c5eedb9dc4c6cc

Return immediately if the needed free bits span a full word to avoid
out-of-bounds shifting.

#syz test

Reported-by: syzbot+9e90a1c5eedb9dc4c6cc@syzkaller.appspotmail.com
Signed-off-by: Matt Jan <zoo868e@gmail.com>
---
Changes in v3: Return the result earlier instead of assert it
Changes in v2: Test if the patch resolve the issue through syzbot and
reference the reporter.

 fs/jfs/jfs_dmap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 974ecf5e0d95..45b7a393b769 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -3012,6 +3012,11 @@ static int dbFindBits(u32 word, int l2nb)
 	int bitno, nb;
 	u32 mask;
 
+	/* return immediately if the number of free bits is a word
+	 */
+	if (l2nb == BUDMIN)
+		return (!!word) << BUDMIN;
+
 	/* get the number of bits.
 	 */
 	nb = 1 << l2nb;
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
[parent not found: <20241025163019.14018-1-zoo868e@gmail.com>]
* [PATCH v2] jfs: UBSAN: shift-out-of-bounds in dbFindBits
  2024-10-25  6:49 syzbot
@ 2024-10-25 15:24 Matt Jan
  2024-10-25 15:39 ` [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2) syzbot
  -1 siblings, 1 reply; 6+ messages in thread
From: Matt Jan @ 2024-10-25 15:24 UTC (permalink / raw)
  To: Dave Kleikamp, jfs-discussion, linux-kernel, Shuah Khan
  Cc: Matt Jan, syzbot+9e90a1c5eedb9dc4c6cc

The starting bit number of free bits should not be >= 32 as it is
0-indexed.Assert that the number of bits is < 32, or if it is 32, the
input word must be 0.

#syz test

Reported-by: syzbot+9e90a1c5eedb9dc4c6cc@syzkaller.appspotmail.com
Signed-off-by: Matt Jan <zoo868e@gmail.com>
---
Changes in v2: Test if the patch resolve the issue through syzbot and
reference the reporter.

 fs/jfs/jfs_dmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 974ecf5e0d95..b9eccf8900eb 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -3015,7 +3015,7 @@ static int dbFindBits(u32 word, int l2nb)
 	/* get the number of bits.
 	 */
 	nb = 1 << l2nb;
-	assert(nb <= DBWORD);
+	assert(nb < DBWORD || (nb == DBWORD && !word));
 
 	/* complement the word so we can use a mask (i.e. 0s represent
 	 * free bits) and compute the mask.
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2)
@ 2024-10-25  6:49 syzbot
  0 siblings, 0 replies; 6+ messages in thread
From: syzbot @ 2024-10-25  6:49 UTC (permalink / raw)
  To: jfs-discussion, linux-kernel, shaggy, syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    c2ee9f594da8 KVM: selftests: Fix build on on non-x86 archi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134fc640580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fc6f8ce8c5369043
dashboard link: https://syzkaller.appspot.com/bug?extid=9e90a1c5eedb9dc4c6cc
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=118f0287980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=128f8a5f980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-c2ee9f59.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8a3541902b13/vmlinux-c2ee9f59.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a00efacc2604/bzImage-c2ee9f59.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/0a96c5cc2569/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9e90a1c5eedb9dc4c6cc@syzkaller.appspotmail.com

ERROR: (device loop0): remounting filesystem as read-only
ERROR: (device loop0): dbDiscardAG: -EIO
ERROR: (device loop0): dbAllocBits: leaf page corrupt
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:3028:55
shift exponent 32 is too large for 32-bit type 'u32' (aka 'unsigned int')
CPU: 0 UID: 0 PID: 5092 Comm: syz-executor128 Not tainted 6.12.0-rc4-syzkaller-00047-gc2ee9f594da8 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
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
 dbFindBits+0x11a/0x1d0 fs/jfs/jfs_dmap.c:3028
 dbAllocDmapLev+0x1e9/0x4a0 fs/jfs/jfs_dmap.c:1985
 dbAllocCtl+0x113/0x920 fs/jfs/jfs_dmap.c:1825
 dbAllocAG+0x28f/0x10b0 fs/jfs/jfs_dmap.c:1364
 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:907 [inline]
 __se_sys_ioctl+0xf9/0x170 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
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f54e7034c99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd37b5c358 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f54e7034c99
RDX: 00000000200000c0 RSI: 00000000c0185879 RDI: 0000000000000004
RBP: 00007f54e70ad5f0 R08: 000055557b4874c0 R09: 000055557b4874c0
R10: 000055557b4874c0 R11: 0000000000000246 R12: 00007ffd37b5c380
R13: 00007ffd37b5c5a8 R14: 431bde82d7b634db R15: 00007f54e707d03b
 </TASK>
---[ end trace ]---


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2025-09-28  1:16 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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     [not found] <87ecrr75n6.fsf@gmail.com>
2025-09-28  1:16 ` [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2) syzbot
2024-11-01  9:59 [PATCH v4] jfs: UBSAN: shift-out-of-bounds in dbFindBits Matt Jan
2024-11-01 10:20 ` [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2) syzbot
  -- strict thread matches above, loose matches on Subject: below --
2024-10-25 17:00 [PATCH v3] jfs: UBSAN: shift-out-of-bounds in dbFindBits Matt Jan
2024-10-25 17:20 ` [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2) syzbot
     [not found] <20241025163019.14018-1-zoo868e@gmail.com>
2024-10-25 16:50 ` syzbot
2024-10-25 15:24 [PATCH v2] jfs: UBSAN: shift-out-of-bounds in dbFindBits Matt Jan
2024-10-25 15:39 ` [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbFindBits (2) syzbot
2024-10-25  6:49 syzbot

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