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| author | Alexey Dobriyan <adobriyan@gmail.com> | 2021-03-14 23:51:14 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-03-14 14:33:27 -0700 |
| commit | c995f12ad8842dbf5cfed113fb52cdd083f5afd1 (patch) | |
| tree | 92dd0fb652dcb361423365b28ee32888ab2257c8 | |
| parent | 70404fe3030ec2dcf339a9730bc03bf0e1f2acf5 (diff) | |
| download | lwn-c995f12ad8842dbf5cfed113fb52cdd083f5afd1.tar.gz lwn-c995f12ad8842dbf5cfed113fb52cdd083f5afd1.zip | |
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>
| -rw-r--r-- | kernel/sys.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index b09fe21e88ff..2e2e3f378d97 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2079,7 +2079,7 @@ static int prctl_set_auxv(struct mm_struct *mm, unsigned long addr, * up to the caller to provide sane values here, otherwise userspace * tools which use this vector might be unhappy. */ - unsigned long user_auxv[AT_VECTOR_SIZE]; + unsigned long user_auxv[AT_VECTOR_SIZE] = {}; if (len > sizeof(user_auxv)) return -EINVAL; |