linux-kernel - UBSAN: shift-out-of-bounds in extAlloc

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Message-ID: <CACkBjsZ5cRX5t0wCr2MfjBp4=-Utn43MzZD4uEyzznvWuUz05A@mail.gmail.com>
Date:   Mon, 11 Oct 2021 09:44:11 +0800
From:   Hao Sun <sunhao.th@...il.com>
To:     shaggy@...nel.org, jfs-discussion@...ts.sourceforge.net
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: UBSAN: shift-out-of-bounds in extAlloc

Hello,

When using Healer to fuzz the latest Linux kernel, the following crash
was triggered.

HEAD commit: 60a9483534ed Merge tag 'warning-fixes-20211005'
git tree: upstream
console output:
https://drive.google.com/file/d/1IM13hIeSrriEEkaACcmQaVYfOJ85xKZQ/view?usp=sharing
kernel config: https://drive.google.com/file/d/1u-ncYGLkq3xqdlNQYJz8-G6Fhf3H-moP/view?usp=sharing

Sorry, I don't have a reproducer for this crash, hope the symbolized
report can help.
If you fix this issue, please add the following tag to the commit:
Reported-by: Hao Sun <sunhao.th@...il.com>

loop9: detected capacity change from 0 to 65534
================================================================================
UBSAN: shift-out-of-bounds in fs/jfs/jfs_extent.c:511:16
shift exponent -1 is negative
CPU: 0 PID: 12367 Comm: syz-executor Not tainted 5.15.0-rc4+ #22
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x8d/0xcf lib/dump_stack.c:106
 ubsan_epilogue+0xa/0x4e lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds+0x161/0x182 lib/ubsan.c:330
 extBalloc fs/jfs/jfs_extent.c:511 [inline]
 extAlloc+0x699/0x6c0 fs/jfs/jfs_extent.c:125
 jfs_get_block+0x290/0x3f0 fs/jfs/inode.c:257
 nobh_write_begin+0x29d/0x990 fs/buffer.c:2648
 jfs_write_begin+0x37/0x80 fs/jfs/inode.c:321
 generic_perform_write+0xce/0x220 mm/filemap.c:3770
 __generic_file_write_iter+0x20d/0x240 mm/filemap.c:3897
 generic_file_write_iter+0x6d/0xd0 mm/filemap.c:3929
 call_write_iter include/linux/fs.h:2163 [inline]
 new_sync_write+0x18d/0x260 fs/read_write.c:507
 vfs_write+0x43b/0x4a0 fs/read_write.c:594
 ksys_write+0xd2/0x120 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x46ae99
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f58ac19fc48 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000078c0a0 RCX: 000000000046ae99
RDX: 00000000ffffff6a RSI: 0000000020043440 RDI: 000000000000000a
RBP: 00000000004e4809 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078c0a0
R13: 0000000000000000 R14: 000000000078c0a0 R15: 00007ffdbff36e60
================================================================================