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pthread: Remove alloca usage from __sem_check_add_mapping

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sem_open already returns EINVAL for input names larger than NAME_MAX,
so it can assume the largest name length with tfind.

Checked on x86_64-linux-gnu.
This commit is contained in:
Adhemerval Zanella 2021-02-03 14:19:27 -03:00
parent da4aea0b5e
commit c1f46f9db7
1 changed files with 17 additions and 6 deletions
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23
sysdeps/pthread/sem_routines.c
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@ -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 SEM_FAILED;
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. */