diff options
| author | Luo Meng <luomeng12@huawei.com> | 2022-05-13 05:52:25 +0300 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-05-20 00:08:54 +0300 |
| commit | d14f5efadd846dbde561bd734318de6a9e6b26e6 (patch) | |
| tree | 86118fd906b38cf1f829daf6e13bb5e1c23ac1a2 /mm | |
| parent | 018160ad314d75b1409129b2247b614a9f35894c (diff) | |
| download | linux-d14f5efadd846dbde561bd734318de6a9e6b26e6.tar.xz | |
tmpfs: fix undefined-behaviour in shmem_reconfigure()
When shmem_reconfigure() calls __percpu_counter_compare(), the second
parameter is unsigned long long. But in the definition of
__percpu_counter_compare(), the second parameter is s64. So when
__percpu_counter_compare() executes abs(count - rhs), UBSAN shows the
following warning:
================================================================================
UBSAN: Undefined behaviour in lib/percpu_counter.c:209:6
signed integer overflow:
0 - -9223372036854775808 cannot be represented in type 'long long int'
CPU: 1 PID: 9636 Comm: syz-executor.2 Tainted: G ---------r- - 4.18.0 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
__dump_stack home/install/linux-rh-3-10/lib/dump_stack.c:77 [inline]
dump_stack+0x125/0x1ae home/install/linux-rh-3-10/lib/dump_stack.c:117
ubsan_epilogue+0xe/0x81 home/install/linux-rh-3-10/lib/ubsan.c:159
handle_overflow+0x19d/0x1ec home/install/linux-rh-3-10/lib/ubsan.c:190
__percpu_counter_compare+0x124/0x140 home/install/linux-rh-3-10/lib/percpu_counter.c:209
percpu_counter_compare home/install/linux-rh-3-10/./include/linux/percpu_counter.h:50 [inline]
shmem_remount_fs+0x1ce/0x6b0 home/install/linux-rh-3-10/mm/shmem.c:3530
do_remount_sb+0x11b/0x530 home/install/linux-rh-3-10/fs/super.c:888
do_remount home/install/linux-rh-3-10/fs/namespace.c:2344 [inline]
do_mount+0xf8d/0x26b0 home/install/linux-rh-3-10/fs/namespace.c:2844
ksys_mount+0xad/0x120 home/install/linux-rh-3-10/fs/namespace.c:3075
__do_sys_mount home/install/linux-rh-3-10/fs/namespace.c:3089 [inline]
__se_sys_mount home/install/linux-rh-3-10/fs/namespace.c:3086 [inline]
__x64_sys_mount+0xbf/0x160 home/install/linux-rh-3-10/fs/namespace.c:3086
do_syscall_64+0xca/0x5c0 home/install/linux-rh-3-10/arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x6a/0xdf
RIP: 0033:0x46b5e9
Code: 5d db fa ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 2b db fa ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f54d5f22c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 000000000077bf60 RCX: 000000000046b5e9
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 000000000077bf60 R08: 0000000020000140 R09: 0000000000000000
R10: 00000000026740a4 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd1fb1592f R14: 00007f54d5f239c0 R15: 000000000077bf6c
================================================================================
[akpm@linux-foundation.org: tweak error message text]
Link: https://lkml.kernel.org/r/20220513025225.2678727-1-luomeng12@huawei.com
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/shmem.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 67a3f3b05fb2..7f41a24ed382 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3476,6 +3476,10 @@ static int shmem_reconfigure(struct fs_context *fc) raw_spin_lock(&sbinfo->stat_lock); inodes = sbinfo->max_inodes - sbinfo->free_inodes; + if (ctx->blocks > S64_MAX) { + err = "Number of blocks too large"; + goto out; + } if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) { if (!sbinfo->max_blocks) { err = "Cannot retroactively limit size"; |