From 83a552b0bb9fc2a5e80a0ab3723c0a80ce1db9f2 Mon Sep 17 00:00:00 2001 From: Wilco Dijkstra Date: Wed, 19 Sep 2018 16:50:18 +0100 Subject: Fix strstr bug with huge needles (bug 23637) The generic strstr in GLIBC 2.28 fails to match huge needles. The optimized AVAILABLE macro reads ahead a large fixed amount to reduce the overhead of repeatedly checking for the end of the string. However if the needle length is larger than this, two_way_long_needle may confuse this as meaning the end of the string and return NULL. This is fixed by adding the needle length to the amount to read ahead. [BZ #23637] * string/test-strstr.c (pr23637): New function. (test_main): Add tests with longer needles. * string/strcasestr.c (AVAILABLE): Fix readahead distance. * string/strstr.c (AVAILABLE): Likewise. --- string/strcasestr.c | 5 +++-- string/strstr.c | 5 +++-- string/test-strstr.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 36 insertions(+), 4 deletions(-) (limited to 'string') diff --git a/string/strcasestr.c b/string/strcasestr.c index 1f6b7b846f..8aa76037dc 100644 --- a/string/strcasestr.c +++ b/string/strcasestr.c @@ -37,8 +37,9 @@ /* Two-Way algorithm. */ #define RETURN_TYPE char * #define AVAILABLE(h, h_l, j, n_l) \ - (((j) + (n_l) <= (h_l)) || ((h_l) += __strnlen ((void*)((h) + (h_l)), 512), \ - (j) + (n_l) <= (h_l))) + (((j) + (n_l) <= (h_l)) \ + || ((h_l) += __strnlen ((void*)((h) + (h_l)), (n_l) + 512), \ + (j) + (n_l) <= (h_l))) #define CHECK_EOL (1) #define RET0_IF_0(a) if (!a) goto ret0 #define CANON_ELEMENT(c) TOLOWER (c) diff --git a/string/strstr.c b/string/strstr.c index 33acdc5442..f74d7189ed 100644 --- a/string/strstr.c +++ b/string/strstr.c @@ -33,8 +33,9 @@ #define RETURN_TYPE char * #define AVAILABLE(h, h_l, j, n_l) \ - (((j) + (n_l) <= (h_l)) || ((h_l) += __strnlen ((void*)((h) + (h_l)), 512), \ - (j) + (n_l) <= (h_l))) + (((j) + (n_l) <= (h_l)) \ + || ((h_l) += __strnlen ((void*)((h) + (h_l)), (n_l) + 512), \ + (j) + (n_l) <= (h_l))) #define CHECK_EOL (1) #define RET0_IF_0(a) if (!a) goto ret0 #define FASTSEARCH(S,C,N) (void*) strchr ((void*)(S), (C)) diff --git a/string/test-strstr.c b/string/test-strstr.c index 8d99716ff3..5861b01b73 100644 --- a/string/test-strstr.c +++ b/string/test-strstr.c @@ -151,6 +151,32 @@ check2 (void) } } +#define N 1024 + +static void +pr23637 (void) +{ + char *h = (char*) buf1; + char *n = (char*) buf2; + + for (int i = 0; i < N; i++) + { + n[i] = 'x'; + h[i] = ' '; + h[i + N] = 'x'; + } + + n[N] = '\0'; + h[N * 2] = '\0'; + + /* Ensure we don't match at the first 'x'. */ + h[0] = 'x'; + + char *exp_result = stupid_strstr (h, n); + FOR_EACH_IMPL (impl, 0) + check_result (impl, h, n, exp_result); +} + static int test_main (void) { @@ -158,6 +184,7 @@ test_main (void) check1 (); check2 (); + pr23637 (); printf ("%23s", ""); FOR_EACH_IMPL (impl, 0) @@ -202,6 +229,9 @@ test_main (void) do_test (15, 9, hlen, klen, 1); do_test (15, 15, hlen, klen, 0); do_test (15, 15, hlen, klen, 1); + + do_test (15, 15, hlen + klen * 4, klen * 4, 0); + do_test (15, 15, hlen + klen * 4, klen * 4, 1); } do_test (0, 0, page_size - 1, 16, 0); -- cgit 1.4.1