On Thu, Aug 25, 2016 at 05:50:36PM +0200, SF Markus Elfring wrote: > From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx> > Date: Thu, 25 Aug 2016 17:45:23 +0200 > > Multiplications for the size determination of memory allocations > indicated that array data structures should be processed. I'm afraid the above comment doesn't mean much to me, can you rephrase? Maybe: "Multiplications for kmalloc size arguments are liable to overflow, potentially causing a potential security issue. Using kmalloc_array() allows the overflow to be caught and the allocation failed. Switch these callsites to kmalloc_array()." > Thus use the corresponding function "kmalloc_array". > > This issue was detected by using the Coccinelle software. > > Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx> > --- > arch/arm/kernel/sys_oabi-compat.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c > index 5f221ac..e624db9 100644 > --- a/arch/arm/kernel/sys_oabi-compat.c > +++ b/arch/arm/kernel/sys_oabi-compat.c > @@ -285,7 +285,7 @@ asmlinkage long sys_oabi_epoll_wait(int epfd, > return -EINVAL; > if (!access_ok(VERIFY_WRITE, events, sizeof(*events) * maxevents)) > return -EFAULT; > - kbuf = kmalloc(sizeof(*kbuf) * maxevents, GFP_KERNEL); > + kbuf = kmalloc_array(maxevents, sizeof(*kbuf), GFP_KERNEL); kmalloc_array() here actually buys us no additional safety at either of the callsites in your patch - we need to have carefully checked the values to ensure they don't overflow prior to the kmalloc for other reasons. That's probably something that should be noted in the commit message too, so reviewers have the confidence that you're not blindly changing everything... Thanks. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
