grep: cap insane -B NUM values to MAX_INT / 8. Fixes bug 2653.

function                                             old     new   delta
grep_main                                            766     779     +13

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/findutils/grep.c b/findutils/grep.c
index 024f276..ff6742a 100644 (file)
--- a/findutils/grep.c
+++ b/findutils/grep.c
@@ -621,30 +621,33 @@ int grep_main(int argc UNUSED_PARAM, char **argv)
 
        /* do normal option parsing */
 #if ENABLE_FEATURE_GREP_CONTEXT
-       int Copt;
+       int Copt, opts;
 
        /* -H unsets -h; -C unsets -A,-B; -e,-f are lists;
         * -m,-A,-B,-C have numeric param */
        opt_complementary = "H-h:C-AB:e::f::m+:A+:B+:C+";
-       getopt32(argv,
+       opts = getopt32(argv,
                OPTSTR_GREP,
                &pattern_head, &fopt, &max_matches,
                &lines_after, &lines_before, &Copt);
 
-       if (option_mask32 & OPT_C) {
+       if (opts & OPT_C) {
                /* -C unsets prev -A and -B, but following -A or -B
                   may override it */
-               if (!(option_mask32 & OPT_A)) /* not overridden */
+               if (!(opts & OPT_A)) /* not overridden */
                        lines_after = Copt;
-               if (!(option_mask32 & OPT_B)) /* not overridden */
+               if (!(opts & OPT_B)) /* not overridden */
                        lines_before = Copt;
        }
        /* sanity checks */
-       if (option_mask32 & (OPT_c|OPT_q|OPT_l|OPT_L)) {
+       if (opts & (OPT_c|OPT_q|OPT_l|OPT_L)) {
                option_mask32 &= ~OPT_n;
                lines_before = 0;
                lines_after = 0;
        } else if (lines_before > 0) {
+               if (lines_before > INT_MAX / sizeof(long long))
+                       lines_before = INT_MAX / sizeof(long long);
+               /* overflow in (lines_before * sizeof(x)) is prevented (above) */
                before_buf = xzalloc(lines_before * sizeof(before_buf[0]));
                IF_EXTRA_COMPAT(before_buf_size = xzalloc(lines_before * sizeof(before_buf_size[0]));)
        }