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Subject[PATCH] Kernel: Improvement in code readability when memdup_user_nul() fails.
Date
From: "Sachin Shukla" <sachin.s5@samsung.com>

There is no need to call kfree() if memdup_user_nul() fails, as no memory
was allocated and the error in the error-valued pointer should be returned.

Signed-off-by: Sachin Shukla <sachin.s5@samsung.com>
---
kernel/user_namespace.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 86b7854..a0ffbf0 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -672,28 +672,31 @@ static ssize_t map_write(struct file *file, const char __user *buf,
*/
mutex_lock(&userns_state_mutex);

- ret = -EPERM;
/* Only allow one successful write to the map */
- if (map->nr_extents != 0)
- goto out;
+ if (map->nr_extents != 0) {
+ mutex_unlock(&userns_state_mutex);
+ return -EPERM;
+ }

/*
* Adjusting namespace settings requires capabilities on the target.
*/
- if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
- goto out;
+ if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN)) {
+ mutex_unlock(&userns_state_mutex);
+ return -EPERM;
+ }

/* Only allow < page size writes at the beginning of the file */
- ret = -EINVAL;
- if ((*ppos != 0) || (count >= PAGE_SIZE))
- goto out;
+ if ((*ppos != 0) || (count >= PAGE_SIZE)) {
+ mutex_unlock(&userns_state_mutex);
+ return -EINVAL;
+ }

/* Slurp in the user data */
kbuf = memdup_user_nul(buf, count);
if (IS_ERR(kbuf)) {
- ret = PTR_ERR(kbuf);
- kbuf = NULL;
- goto out;
+ mutex_unlock(&userns_state_mutex);
+ return PTR_ERR(kbuf);
}

/* Parse the user data */
--
1.7.9.5
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