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Merge branch 'fix-bpf_strnstr-len-error'

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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: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko
2025-08-29 11:32:03 -07:00
committed by Alexei Starovoitov
parent 387be23a95 6624fb2f33
commit 813104c192
2 changed files with 14 additions and 3 deletions
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9
kernel/bpf/helpers.c
View File

@@ -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;

8
tools/testing/selftests/bpf/progs/string_kfuncs_success.c
View File

@@ -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";