regex: fix read overrun [BZ #24114]

Problem found by AddressSanitizer, reported by Hongxu Chen in:
https://debbugs.gnu.org/34140
* posix/regexec.c (proceed_next_node):
Do not read past end of input buffer.

(cherry picked from commit 583dd860d5b833037175247230a328f0050dbfe9)

diff --git a/ChangeLog b/ChangeLog
index 90558e434cea41d95c3de1046e466964db03cee3..fb88626efe1d3a72366357be26c5168798e68ef0 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-01-31  Paul Eggert  <eggert@cs.ucla.edu>
+
+       regex: fix read overrun [BZ #24114]
+       Problem found by AddressSanitizer, reported by Hongxu Chen in:
+       https://debbugs.gnu.org/34140
+       * posix/regexec.c (proceed_next_node):
+       Do not read past end of input buffer.
+
 2019-03-13  Stefan Liebler  <stli@linux.ibm.com>
 
        * elf/dl-sysdep.c (_dl_show_auxv): Remove condition and always

diff --git a/posix/regexec.c b/posix/regexec.c
index 91d5a797b82e2679ceab74238416de06693e46ea..084b1222d95b62eb2930166060174ef78cb74b02 100644 (file)
--- a/posix/regexec.c
+++ b/posix/regexec.c
@@ -1293,8 +1293,10 @@ proceed_next_node (const re_match_context_t *mctx, Idx nregs, regmatch_t *regs,
              else if (naccepted)
                {
                  char *buf = (char *) re_string_get_buffer (&mctx->input);
-                 if (memcmp (buf + regs[subexp_idx].rm_so, buf + *pidx,
-                             naccepted) != 0)
+                 if (mctx->input.valid_len - *pidx < naccepted
+                     || (memcmp (buf + regs[subexp_idx].rm_so, buf + *pidx,
+                                 naccepted)
+                         != 0))
                    return -1;
                }
            }