From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Luo Meng <luomeng12@huawei.com>, Jeff Layton <jlayton@kernel.org>,
Sasha Levin <sashal@kernel.org>,
linux-fsdevel@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 01/87] locks: Fix UBSAN undefined behaviour in flock64_to_posix_lock
Date: Tue, 22 Dec 2020 21:19:37 -0500 [thread overview]
Message-ID: <20201223022103.2792705-1-sashal@kernel.org> (raw)
From: Luo Meng <luomeng12@huawei.com>
[ Upstream commit 16238415eb9886328a89fe7a3cb0b88c7335fe16 ]
When the sum of fl->fl_start and l->l_len overflows,
UBSAN shows the following warning:
UBSAN: Undefined behaviour in fs/locks.c:482:29
signed integer overflow: 2 + 9223372036854775806
cannot be represented in type 'long long int'
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xe4/0x14e lib/dump_stack.c:118
ubsan_epilogue+0xe/0x81 lib/ubsan.c:161
handle_overflow+0x193/0x1e2 lib/ubsan.c:192
flock64_to_posix_lock fs/locks.c:482 [inline]
flock_to_posix_lock+0x595/0x690 fs/locks.c:515
fcntl_setlk+0xf3/0xa90 fs/locks.c:2262
do_fcntl+0x456/0xf60 fs/fcntl.c:387
__do_sys_fcntl fs/fcntl.c:483 [inline]
__se_sys_fcntl fs/fcntl.c:468 [inline]
__x64_sys_fcntl+0x12d/0x180 fs/fcntl.c:468
do_syscall_64+0xc8/0x5a0 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fix it by parenthesizing 'l->l_len - 1'.
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/locks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/locks.c b/fs/locks.c
index 28270e74be342..465917362eca3 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -479,7 +479,7 @@ static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
if (l->l_len > 0) {
if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
return -EOVERFLOW;
- fl->fl_end = fl->fl_start + l->l_len - 1;
+ fl->fl_end = fl->fl_start + (l->l_len - 1);
} else if (l->l_len < 0) {
if (fl->fl_start + l->l_len < 0)
--
2.27.0
next reply other threads:[~2020-12-23 2:53 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-23 2:19 Sasha Levin [this message]
2020-12-23 2:19 ` [PATCH AUTOSEL 4.19 07/87] fcntl: Fix potential deadlock in send_sig{io, urg}() Sasha Levin
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