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 1a40e277eb5e1..11bb382a23c2e 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -488,7 +488,7 @@ 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)