On 2020-11-09 8:07 p.m., Qian Cai wrote:
On Mon, 2020-11-09 at 13:04 +0000, Colin King wrote:From: Colin Ian King <colin.king@xxxxxxxxxxxxx> Currently the allocation of cpulist is based on the length of buf but does not include the addition end of string '\0' terminator. Static analysis is reporting this as a potential out-of-bounds access on cpulist. Fix this by allocating enough space for the additional '\0' terminator. Addresses-Coverity: ("Out-of-bounds access") Fixes: 65987e67f7ff ("cpumask: add "last" alias for cpu list specifications")Yeah, this bad commit also introduced KASAN errors everywhere and then will disable lockdep that makes our linux-next CI miserable. Confirmed that this patch will fix it.
I appreciate the reports reminding me why I hate touching string handling. But let us not lose sight of why linux-next exists. We want to encourage code to appear there as a sounding board before it goes mainline, so we can fix things and not pollute mainline git history with those trivialities. If you've decided to internalize linux-next as part of your CI, then great, but do note that does not elevate linux-next to some pristine status for the world at large. That only means you have to watch more closely what is going on. If you want to declare linux-next unbreakable -- well that would scare away others to get the multi-arch or multi-config coverage that they may not be able to do themselves. We are not going to do that. I have (hopefully) fixed the "bad commit" in v2 -- as part of the implicit linux-next rule "you broke it, you better fix it ASAP". But "bad" and "miserable" can be things that might scare people off of making use of linux-next for what it is meant to be for. And I am not OK with that. Thanks, Paul. --
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx> --- lib/cpumask.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/cpumask.c b/lib/cpumask.c index 34ecb3005941..cb8a3ef0e73e 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -185,7 +185,7 @@ int __ref cpulist_parse(const char *buf, struct cpumask *dstp) { int r; char *cpulist, last_cpu[5]; /* NR_CPUS <= 9999 */ - size_t len = strlen(buf); + size_t len = strlen(buf) + 1; bool early = !slab_is_available();if (!strcmp(buf, "all")) {
