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elf: Check for empty tokens before dynamic string token expansion [BZ #22625]
The fillin_rpath function in elf/dl-load.c loops over each RPATH or RUNPATH tokens and interprets empty tokens as the current directory ("./"). In practice the check for empty token is done *after* the dynamic string token expansion. The expansion process can return an empty string for the $ORIGIN token if __libc_enable_secure is set or if the path of the binary can not be determined (/proc not mounted). Fix that by moving the check for empty tokens before the dynamic string token expansion. In addition, check for NULL pointer or empty strings return by expand_dynamic_string_token. The above changes highlighted a bug in decompose_rpath, an empty array is represented by the first element being NULL at the fillin_rpath level, but by using a -1 pointer in decompose_rpath and other functions. Changelog: [BZ #22625] * elf/dl-load.c (fillin_rpath): Check for empty tokens before dynamic string token expansion. Check for NULL pointer or empty string possibly returned by expand_dynamic_string_token. (decompose_rpath): Check for empty path after dynamic string token expansion.
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ChangeLog
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ChangeLog
@ -1,3 +1,13 @@
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2017-12-30 Aurelien Jarno <aurelien@aurel32.net>
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Dmitry V. Levin <ldv@altlinux.org>
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[BZ #22625]
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* elf/dl-load.c (fillin_rpath): Check for empty tokens before dynamic
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string token expansion. Check for NULL pointer or empty string possibly
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returned by expand_dynamic_string_token.
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(decompose_rpath): Check for empty path after dynamic string
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token expansion.
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2017-12-29 Dmitry V. Levin <ldv@altlinux.org>
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[BZ #22433]
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4
NEWS
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NEWS
@ -164,6 +164,10 @@ Security related changes:
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CVE-2017-1000366 has been applied, but it is mentioned here only because
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of the CVE assignment.) Reported by Qualys.
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CVE-2017-16997: Incorrect handling of RPATH or RUNPATH containing $ORIGIN
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for AT_SECURE or SUID binaries could be used to load libraries from the
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current directory.
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The following bugs are resolved with this release:
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[The release manager will add the list generated by
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@ -389,32 +389,41 @@ fillin_rpath (char *rpath, struct r_search_path_elem **result, const char *sep,
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{
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char *cp;
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size_t nelems = 0;
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char *to_free;
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while ((cp = __strsep (&rpath, sep)) != NULL)
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{
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struct r_search_path_elem *dirp;
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char *to_free = NULL;
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size_t len = 0;
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to_free = cp = expand_dynamic_string_token (l, cp);
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size_t len = strlen (cp);
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/* `strsep' can pass an empty string. This has to be
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interpreted as `use the current directory'. */
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if (len == 0)
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/* `strsep' can pass an empty string. */
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if (*cp != '\0')
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{
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static const char curwd[] = "./";
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cp = (char *) curwd;
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to_free = cp = expand_dynamic_string_token (l, cp);
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/* expand_dynamic_string_token can return NULL in case of empty
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path or memory allocation failure. */
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if (cp == NULL)
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continue;
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/* Compute the length after dynamic string token expansion and
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ignore empty paths. */
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len = strlen (cp);
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if (len == 0)
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{
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free (to_free);
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continue;
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}
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/* Remove trailing slashes (except for "/"). */
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while (len > 1 && cp[len - 1] == '/')
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--len;
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/* Now add one if there is none so far. */
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if (len > 0 && cp[len - 1] != '/')
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cp[len++] = '/';
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}
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/* Remove trailing slashes (except for "/"). */
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while (len > 1 && cp[len - 1] == '/')
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--len;
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/* Now add one if there is none so far. */
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if (len > 0 && cp[len - 1] != '/')
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cp[len++] = '/';
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/* See if this directory is already known. */
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for (dirp = GL(dl_all_dirs); dirp != NULL; dirp = dirp->next)
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if (dirp->dirnamelen == len && memcmp (cp, dirp->dirname, len) == 0)
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@ -569,6 +578,14 @@ decompose_rpath (struct r_search_path_struct *sps,
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necessary. */
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free (copy);
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/* There is no path after expansion. */
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if (result[0] == NULL)
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{
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free (result);
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sps->dirs = (struct r_search_path_elem **) -1;
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return false;
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}
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sps->dirs = result;
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/* The caller will change this value if we haven't used a real malloc. */
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sps->malloced = 1;
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