From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
[ Upstream commit c995f12ad8842dbf5cfed113fb52cdd083f5afd1 ]
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@xxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/sys.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sys.c b/kernel/sys.c
index 2e4f017f7c5a..03fc0152cc54 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2005,7 +2005,7 @@ 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;
--
2.30.1
