Add regex to delta code so we don't segfault when reading line

If the delta line doesn't match our regex, we won't go and process it,
possibly walking off the end of the string.

Signed-off-by: Dan McGee <dan@archlinux.org>

2 files changed, 19 insertions, 1 deletions

diff --git a/lib/libalpm/be_files.c b/lib/libalpm/be_files.c
index 0658a661..b9ff6464 100644
--- a/lib/libalpm/be_files.c
+++ b/lib/libalpm/be_files.c
@@ -618,7 +618,10 @@ int _alpm_db_read(pmdb_t *db, pmpkg_t *info, pmdbinfrq_t inforeq)
 				_alpm_strtrim(line);
 				if(strcmp(line, "%DELTAS%") == 0) {
 					while(fgets(line, 512, fp) && strlen(_alpm_strtrim(line))) {
-						info->deltas = alpm_list_add(info->deltas, _alpm_delta_parse(line));
+						pmdelta_t *delta = _alpm_delta_parse(line);
+						if(delta) {
+							info->deltas = alpm_list_add(info->deltas, delta);
+						}
 					}
 				}
 			}
diff --git a/lib/libalpm/delta.c b/lib/libalpm/delta.c
index 22d9beb4..8dce7e3b 100644
--- a/lib/libalpm/delta.c
+++ b/lib/libalpm/delta.c
@@ -22,6 +22,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
+#include <sys/types.h>
+#include <regex.h>
 
 /* libalpm */
 #include "delta.h"
@@ -257,6 +259,19 @@ pmdelta_t *_alpm_delta_parse(char *line)
 {
 	pmdelta_t *delta;
 	char *tmp = line, *tmp2;
+	regex_t reg;
+
+	regcomp(&reg,
+			"^[^[:space:]]* [[:xdigit:]]{32}"
+			" [^[:space:]]* [[:xdigit:]]{32}"
+			" [^[:space:]]* [[:xdigit:]]{32} [[:digit:]]*$",
+			REG_EXTENDED | REG_NOSUB | REG_NEWLINE);
+	if(regexec(&reg, line, 0, 0, 0) != 0) {
+		/* delta line is invalid, return NULL */
+		regfree(&reg);
+		return(NULL);
+	}
+	regfree(&reg);
 
 	CALLOC(delta, 1, sizeof(pmdelta_t), RET_ERR(PM_ERR_MEMORY, NULL));