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 e5011123eb7dc3669803437625a0b19e8f42c567..0ef60fa5ac556c9e39466b2bf4b24604fcec9586 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.
+
 2018-11-07  Andreas Schwab  <schwab@suse.de>
 
        [BZ #23864]

diff --git a/posix/regexec.c b/posix/regexec.c
index 73644c2341336e6655980a6eb29bad2110ea73a2..06b8487c3e3eab0e47c04e6dd59a6205f58838d1 100644 (file)
--- a/posix/regexec.c
+++ b/posix/regexec.c
@@ -1289,8 +1289,10 @@ 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;
                }
            }