[3/3] pthread: Remove alloca usage from __sem_check_add_mapping
Commit Message
sem_open already returns EINVAL for input names larger than NAME_MAX,
so it can assume the largest name length to with tfind.
Checked on x86_64-linux-gnu.
---
sysdeps/pthread/sem_routines.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
Comments
* Adhemerval Zanella via Libc-alpha:
> sem_open already returns EINVAL for input names larger than NAME_MAX,
> so it can assume the largest name length to with tfind.
Typo: “to with”
> @@ -61,6 +70,9 @@ sem_t *
> __sem_check_add_mapping (const char *name, int fd, sem_t *existing)
> {
> size_t namelen = strlen (name);
> + if (namelen > NAME_MAX)
> + return NULL;
> +
> sem_t *result = SEM_FAILED;
Should this return SEM_FAILED?
Thanks,
Florian
On 07/02/2021 06:29, Florian Weimer wrote:
> * Adhemerval Zanella via Libc-alpha:
>
>> sem_open already returns EINVAL for input names larger than NAME_MAX,
>> so it can assume the largest name length to with tfind.
>
> Typo: “to with”
Ack.
>
>> @@ -61,6 +70,9 @@ sem_t *
>> __sem_check_add_mapping (const char *name, int fd, sem_t *existing)
>> {
>> size_t namelen = strlen (name);
>> + if (namelen > NAME_MAX)
>> + return NULL;
>> +
>> sem_t *result = SEM_FAILED;
>
> Should this return SEM_FAILED?
It should, I have fixed it.
>
> Thanks,
> Florian
>
@@ -31,6 +31,15 @@ struct inuse_sem
char name[];
};
+struct search_sem
+{
+ dev_t dev;
+ ino_t ino;
+ int refcnt;
+ sem_t *sem;
+ char name[NAME_MAX];
+};
+
/* Comparison function for search of existing mapping. */
static int
sem_search (const void *a, const void *b)
@@ -61,6 +70,9 @@ sem_t *
__sem_check_add_mapping (const char *name, int fd, sem_t *existing)
{
size_t namelen = strlen (name);
+ if (namelen > NAME_MAX)
+ return NULL;
+
sem_t *result = SEM_FAILED;
/* Get the information about the file. */
@@ -71,13 +83,12 @@ __sem_check_add_mapping (const char *name, int fd, sem_t *existing)
lll_lock (sem_mappings_lock, LLL_PRIVATE);
/* Search for an existing mapping given the information we have. */
- struct inuse_sem *fake;
- fake = (struct inuse_sem *) alloca (sizeof (*fake) + namelen);
- memcpy (fake->name, name, namelen);
- fake->dev = st.st_dev;
- fake->ino = st.st_ino;
+ struct search_sem fake;
+ memcpy (fake.name, name, namelen);
+ fake.dev = st.st_dev;
+ fake.ino = st.st_ino;
- struct inuse_sem **foundp = __tfind (fake, &sem_mappings, sem_search);
+ struct inuse_sem **foundp = __tfind (&fake, &sem_mappings, sem_search);
if (foundp != NULL)
{
/* There is already a mapping. Use it. */