[PATCH] kernel/sys.c: fix prctl_set_auxv to use sizeof instead of user-supplied len

[Aiden Bowling <aidenlbowling56@gmail.com>]

prctl_set_auxv() passed the user-supplied 'len' to memcpy() when copying
into mm->saved_auxv, instead of sizeof(user_auxv). Since user_auxv is
already sized to the full auxv buffer, using 'len' risks a partial write
if the caller supplies a smaller value. Use sizeof(user_auxv) to always
copy the full buffer after validation.

Signed-off-by: Aiden Bowling <aidenlbowling56@gmail.com>
---
 kernel/sys.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 62e842055cc9..d3f5229649e3 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2189,7 +2189,7 @@ static int prctl_set_auxv(struct mm_struct *mm, unsigned long addr,
 	BUILD_BUG_ON(sizeof(user_auxv) != sizeof(mm->saved_auxv));
 
 	task_lock(current);
-	memcpy(mm->saved_auxv, user_auxv, len);
+	memcpy(mm->saved_auxv, user_auxv, sizeof(user_auxv));
 	task_unlock(current);
 
 	return 0;

base-commit: e43ffb69e0438cddd72aaa30898b4dc446f664f8
-- 
2.54.0