[review] Avoid zero-length array at the end of struct link_map [BZ #25097]

["Carlos O'Donell (Code Review)" <gerrit at gnutoolchain-gerrit dot osci dot io>]

Carlos O'Donell has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/glibc/+/488
......................................................................


Patch Set 1:

(4 comments)

| --- include/link.h
| +++ include/link.h
| @@ -337,9 +329,19 @@ #endif
|  
| +/* Information used by audit modules.  For most link maps, this data
| +   immediate follows the link map in memory.  For the dynamic linker,
| +   it is allocated separately.  See link_map_audit_state in
| +   <ldsodefs.h>.  */
| +struct auditstate
| +{
| +  uintptr_t cookie;
| +  unsigned int bindflags;
| +};

PS1, Line 338:

Done

| +
|  
|  #if __ELF_NATIVE_CLASS == 32
|  # define symbind symbind32
|  #elif __ELF_NATIVE_CLASS == 64
|  # define symbind symbind64
|  #else
|  # error "__ELF_NATIVE_CLASS must be defined"
|  #endif
| --- sysdeps/generic/ldsodefs.h
| +++ sysdeps/generic/ldsodefs.h
| @@ -381,15 +381,16 @@ #endif
|  
| -  /* Structure describing the dynamic linker itself.  We need to
| -     reserve memory for the data the audit libraries need.  */
| +  /* Structure describing the dynamic linker itself.  */
|    EXTERN struct link_map _dl_rtld_map;
|  #ifdef SHARED
| -  struct auditstate audit_data[DL_NNS];
| +  /* Used to store the audit information for the link map of the
| +     dynamic loader.  */
| +  struct auditstate _dl_rtld_auditstate[DL_NNS];

PS1, Line 387:

Done

|  #endif
|  
|  #if defined SHARED && defined _LIBC_REENTRANT \
|      && defined __rtld_lock_default_lock_recursive
|    EXTERN void (*_dl_rtld_lock_recursive) (void *);
|    EXTERN void (*_dl_rtld_unlock_recursive) (void *);
|  #endif
|  
|    /* Get architecture specific definitions.  */

 ...

| @@ -1175,13 +1176,21 @@ rtld_active (void)
|    return GLRO(dl_init_all_dirs) != NULL;
|  }
|  
|  static inline struct auditstate *
|  link_map_audit_state (struct link_map *l, size_t index)
|  {
| -  return &l->l_audit[index];
| +  if (l == &GL (dl_rtld_map))
| +    /* The auditstate array is stored separately.  */
| +    return &GL (dl_rtld_auditstate) [index];

PS1, Line 1184:

Done

| +  else
| +    {
| +      /* The auditstate array follows the link map in memory.  */
| +      struct auditstate *base = (struct auditstate *) (l + 1);
| +      return &base[index];

PS1, Line 1189:

Done

| +    }
|  }
|  #endif /* SHARED */
|  
|  __END_DECLS
|  
|  #endif /* ldsodefs.h */

-- 
Gerrit-Project: glibc
Gerrit-Branch: master
Gerrit-Change-Id: Ic911100730f9124d4ea977ead8e13cee64b84d45
Gerrit-Change-Number: 488
Gerrit-PatchSet: 1
Gerrit-Owner: Florian Weimer <fweimer@redhat.com>
Gerrit-Reviewer: Carlos O'Donell <carlos@redhat.com>
Gerrit-Comment-Date: Thu, 14 Nov 2019 14:59:34 +0000
Gerrit-HasComments: Yes
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Comment-In-Reply-To: Carlos O'Donell <carlos@redhat.com>
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