On Fri, Feb 23, 2024 at 04:05:16PM -0500, Paul Moore wrote: > On Fri, Feb 23, 2024 at 3:04 PM Mickaël Salaün <mic@xxxxxxxxxxx> wrote: > > > > On Fri, Feb 23, 2024 at 08:59:34PM +0100, Mickaël Salaün wrote: > > > On Fri, Feb 23, 2024 at 08:05:45PM +0100, Mickaël Salaün wrote: > > > > selinux_lsm_getattr() may not initialize the value's pointer in some > > > > case. As for proc_pid_attr_read(), initialize this pointer to NULL in > > > > selinux_getselfattr() to avoid an UAF in the kfree() call. > > > > > > Not UAF but NULL pointer dereference (both patches)... > > > > Well, that may be the result (as observed with the kfree() call), but > > the cause is obviously an uninitialized pointer. > > Adding the SELinux list to the CC line; SELinux folks the original post is here: > > * https://lore.kernel.org/all/20240223190546.3329966-1-mic@xxxxxxxxxxx > > Thanks for finding this and testing the patch, based on our off-list > discussion, do you mind if I add a Suggested-by? Looking at this a Sure! I was in a hurry and didn't give it the attention it needed... > bit more I think we'll want to make a few changes to > selinux_lsm_getattr() later, but this patch is a good one for stable > as it not only fixes the bug, but it is a trivial one-liner with very > low risk. > > I do think we need to tweak the commit description a bit, what do you > think of the following? > > "selinux_getselfattr() doesn't properly initialize the string > pointer it passes to selinux_lsm_getattr() which can cause a > problem when an attribute hasn't been explicitly set; > selinux_lsm_getattr() returns 0/success, but does not set or > initialize the string label/attribute. Failure to properly > initialize the string causes problems later in > selinux_getselfattr() when the function attempts to kfree() > the string." Much better!
