[PATCH -mm] prctl: Return -EFAULT on auxv fetching failure

From: Cyrill Gorcunov
Date: Wed Aug 27 2014 - 07:04:03 EST

Dan reported that returning bytes left if copy_from_user failed
is a bad option, return traditional -EFAULT instead.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Dan, this is not for current linux-next, but for Andrew's -mm
queue, since he has prctl code already updated with v4 of the
former patch.

kernel/sys.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

Index: linux-2.6.git/kernel/sys.c
--- linux-2.6.git.orig/kernel/sys.c
+++ linux-2.6.git/kernel/sys.c
@@ -1814,11 +1814,10 @@ static int prctl_set_mm_map(int opt, con

if (prctl_map.auxv_size) {
memset(user_auxv, 0, sizeof(user_auxv));
- error = copy_from_user(user_auxv,
- (const void __user *)prctl_map.auxv,
- prctl_map.auxv_size);
- if (error)
- return error;
+ if (copy_from_user(user_auxv,
+ (const void __user *)prctl_map.auxv,
+ prctl_map.auxv_size))
+ return -EFAULT;

/* Last entry must be AT_NULL as specification requires */
user_auxv[AT_VECTOR_SIZE - 2] = AT_NULL;
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