tree 92dd0fb652dcb361423365b28ee32888ab2257c8
parent 70404fe3030ec2dcf339a9730bc03bf0e1f2acf5
author Alexey Dobriyan <adobriyan@gmail.com> 1615755074 +0300
committer Linus Torvalds <torvalds@linux-foundation.org> 1615757607 -0700

prctl: fix PR_SET_MM_AUXV kernel stack leak

Doing a

	prctl(PR_SET_MM, PR_SET_MM_AUXV, addr, 1);

will copy 1 byte from userspace to (quite big) on-stack array
and then stash everything to mm->saved_auxv.
AT_NULL terminator will be inserted at the very end.

/proc/*/auxv handler will find that AT_NULL terminator
and copy original stack contents to userspace.

This devious scheme requires CAP_SYS_RESOURCE.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>