From 046a28a8828264ab8822cb9729892743fb18a5ed Mon Sep 17 00:00:00 2001 From: zhongjiang Date: Wed, 28 Jun 2017 08:01:47 +1000 Subject: [PATCH] kernel/signal.c: avoid undefined behaviour in kill_something_info When running kill(72057458746458112, 0) in userspace I hit the following issue. [ 304.606353] UBSAN: Undefined behaviour in kernel/signal.c:1462:11 [ 304.612622] negation of -2147483648 cannot be represented in type 'int': [ 304.619516] CPU: 226 PID: 9849 Comm: test Tainted: G B ---- ------- 3.10.0-327.53.58.70.x86_64_ubsan+ #116 [ 304.630692] Hardware name: Huawei Technologies Co., Ltd. RH8100 V3/BC61PBIA, BIOS BLHSV028 11/11/2014 [ 304.640168] ffffffff825ded30 000000005dc276fa ffff883c3a4b7ce0 ffffffff81d6eb06 [ 304.647870] ffff883c3a4b7cf8 ffffffff81d6ebb9 ffffffff825ded20 ffff883c3a4b7de8 [ 304.655584] ffffffff81d6fc89 0000000041b58ab3 ffffffff8228d6d8 ffffffff81d6fb80 [ 304.663299] Call Trace: [ 304.665827] [] dump_stack+0x19/0x1b [ 304.671115] [] ubsan_epilogue+0xd/0x50 [ 304.676668] [] __ubsan_handle_negate_overflow+0x109/0x14e [ 304.683917] [] ? __ubsan_handle_divrem_overflow+0x1df/0x1df [ 304.691353] [] ? __inc_zone_state+0x29/0xf0 [ 304.697358] [] ? __lru_cache_add+0x8f/0xe0 [ 304.703272] [] ? lru_cache_add+0xe/0x10 [ 304.708921] [] ? map_id_up+0xad/0xe0 [ 304.714306] [] SYSC_kill+0x43e/0x4d0 [ 304.725359] [] ? lg_local_unlock+0x20/0xd0 [ 304.736978] [] ? kill_pid+0x20/0x20 [ 304.747928] [] ? __pmd_alloc+0x180/0x180 [ 304.759273] [] ? mntput+0x3b/0x70 [ 304.769919] [] ? __do_page_fault+0x2bc/0x650 [ 304.781462] [] ? __audit_syscall_entry+0x1f7/0x2a0 [ 304.793476] [] SyS_kill+0xe/0x10 [ 304.803859] [] system_call_fastpath+0x16/0x1b Add code to avoid the UBSAN detection. Link: http://lkml.kernel.org/r/1496670008-59084-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhongjiang Cc: Oleg Nesterov Cc: Michal Hocko Cc: Vlastimil Babka Cc: Xishi Qiu Signed-off-by: Andrew Morton --- kernel/signal.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/signal.c b/kernel/signal.c index 45b4c1ffe14ef4..34a1628ee635a1 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1401,6 +1401,13 @@ static int kill_something_info(int sig, struct siginfo *info, pid_t pid) return ret; } + /* + * -INT_MIN is undefined, it need to exclude following case to + * avoid the UBSAN detection. + */ + if (pid == INT_MIN) + return -ESRCH; + read_lock(&tasklist_lock); if (pid != -1) { ret = __kill_pgrp_info(sig, info,