diff mbox series

rt: fix shm_open not set ENAMETOOLONG when name exceeds {_POSIX_PATH_MAX}

Message ID 20230307094546.633473-1-abushwangs@gmail.com
State Superseded
Headers
Series rt: fix shm_open not set ENAMETOOLONG when name exceeds {_POSIX_PATH_MAX} |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

abushwang March 7, 2023, 9:45 a.m. UTC 
  according to man-pages-posix-2017, shm_open() function may fail if the length
of the name argument exceeds {_POSIX_PATH_MAX} and set ENAMETOOLONG

Signed-off-by: abushwang <abushwangs@gmail.com>
---
 posix/shm-directory.c | 5 +++--
 rt/shm_open.c         | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

Comments

Xi Ruoyao March 7, 2023, 10:02 a.m. UTC | #1 
On Tue, 2023-03-07 at 17:45 +0800, abushwang via Libc-alpha wrote:
> according to man-pages-posix-2017, shm_open() function may fail if the length
> of the name argument exceeds {_POSIX_PATH_MAX} and set ENAMETOOLONG
> 
> Signed-off-by: abushwang <abushwangs@gmail.com>

Please use [PATCH v2] or v3, v4, ... into the title when you update the patch.

/* snip */

>  int
>  __shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix)
> @@ -54,9 +55,9 @@ __shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix)
>    if (sem_prefix)
>      alloc_buffer_copy_bytes (&buffer, "sem.", strlen ("sem."));
>    alloc_buffer_copy_bytes (&buffer, name, namelen + 1);
> -  if (namelen == 0 || memchr (name, '/', namelen) != NULL
> +  if (namelen == 0 || namelen > NAME_MAX || memchr (name, '/', namelen) != NULL

You can't just reject any namelen > NAMEMAX because a "may" clause in
the specification.  You may only do that if the allocation fails.

What you are doing is like: the specification of a capacitor says it may
(not "must" or "shall"!) blow up if the temperature is > 90C, then you
add a bomb into the capacitor which blows up when the temperature
reaches 90C.  It's definitely wrong. 

I was not telling you to make the code more compact.
diff mbox series

Patch

diff --git a/posix/shm-directory.c b/posix/shm-directory.c
index 86d9fd8e4f..ca9d9f2f77 100644
--- a/posix/shm-directory.c
+++ b/posix/shm-directory.c
@@ -25,6 +25,7 @@ 
 #include <string.h>
 #include <sys/mman.h>
 #include <fcntl.h>
+#include <errno.h>
 
 int
 __shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix)
@@ -54,9 +55,9 @@  __shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix)
   if (sem_prefix)
     alloc_buffer_copy_bytes (&buffer, "sem.", strlen ("sem."));
   alloc_buffer_copy_bytes (&buffer, name, namelen + 1);
-  if (namelen == 0 || memchr (name, '/', namelen) != NULL
+  if (namelen == 0 || namelen > NAME_MAX || memchr (name, '/', namelen) != NULL
       || alloc_buffer_has_failed (&buffer))
-    return -1;
+    return namelen ? ENAMETOOLONG : EINVAL;
   return 0;
 }
 libc_hidden_def (__shm_get_name)
diff --git a/rt/shm_open.c b/rt/shm_open.c
index 6c1f4d604f..fc1dc96bb4 100644
--- a/rt/shm_open.c
+++ b/rt/shm_open.c
@@ -30,9 +30,10 @@  int
 __shm_open (const char *name, int oflag, mode_t mode)
 {
   struct shmdir_name dirname;
-  if (__shm_get_name (&dirname, name, false) != 0)
+  int ret =__shm_get_name (&dirname, name, false);
+  if (ret != 0)
     {
-      __set_errno (EINVAL);
+      __set_errno (ret);
       return -1;
     }