Commit 813104c1 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

Merge branch 'fix-bpf_strnstr-len-error' 

Rong Tao says:

====================
Fix bpf_strnstr() wrong 'len' parameter, bpf_strnstr("open", "open", 4)
should return 0 instead of -ENOENT. And fix a more general case when s2
is a suffix of the first len characters of s1.
====================

Link: https://patch.msgid.link/tencent_E72A37AF03A3B18853066E421B5969976208@qq.com


Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 387be23a 6624fb2f

kernel/bpf/helpers.c

+8 −1
Original line number Diff line number Diff line
@@ -3664,10 +3664,17 @@ __bpf_kfunc int bpf_strnstr(const char *s1__ign, const char *s2__ign, size_t len 


	guard(pagefault)();

	for (i = 0; i < XATTR_SIZE_MAX; i++) {

		for (j = 0; i + j < len && j < XATTR_SIZE_MAX; j++) {

		for (j = 0; i + j <= len && j < XATTR_SIZE_MAX; j++) {

			__get_kernel_nofault(&c2, s2__ign + j, char, err_out);

			if (c2 == '\0')

				return i;

			/*

			 * We allow reading an extra byte from s2 (note the

			 * `i + j <= len` above) to cover the case when s2 is

			 * a suffix of the first len chars of s1.

			 */

			if (i + j == len)

				break;

			__get_kernel_nofault(&c1, s1__ign + j, char, err_out);

			if (c1 == '\0')

				return -ENOENT;

tools/testing/selftests/bpf/progs/string_kfuncs_success.c

+6 −2
Original line number Diff line number Diff line
@@ -30,8 +30,12 @@ __test(2) int test_strcspn(void *ctx) { return bpf_strcspn(str, "lo"); } 
__test(6) int test_strstr_found(void *ctx) { return bpf_strstr(str, "world"); }

__test(-ENOENT) int test_strstr_notfound(void *ctx) { return bpf_strstr(str, "hi"); }

__test(0) int test_strstr_empty(void *ctx) { return bpf_strstr(str, ""); }

__test(0) int test_strnstr_found(void *ctx) { return bpf_strnstr(str, "hello", 6); }

__test(-ENOENT) int test_strnstr_notfound(void *ctx) { return bpf_strnstr(str, "hi", 10); }

__test(0) int test_strnstr_found1(void *ctx) { return bpf_strnstr("", "", 0); }

__test(0) int test_strnstr_found2(void *ctx) { return bpf_strnstr(str, "hello", 5); }

__test(0) int test_strnstr_found3(void *ctx) { return bpf_strnstr(str, "hello", 6); }

__test(-ENOENT) int test_strnstr_notfound1(void *ctx) { return bpf_strnstr(str, "hi", 10); }

__test(-ENOENT) int test_strnstr_notfound2(void *ctx) { return bpf_strnstr(str, "hello", 4); }

__test(-ENOENT) int test_strnstr_notfound3(void *ctx) { return bpf_strnstr("", "a", 0); }

__test(0) int test_strnstr_empty(void *ctx) { return bpf_strnstr(str, "", 1); }



char _license[] SEC("license") = "GPL";