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selftests/bpf: Fix invalid use of strncat in test_sockmap 

strncat()'s third argument is how many bytes will be added *in addition* to
already existing bytes in destination. Plus extra zero byte will be added
after that. So existing use in test_sockmap has many opportunities to overflow
the string and cause memory corruptions. And in this case, GCC complains for
a good reason.

Fixes: 16962b2404 ("bpf: sockmap, add selftests")
Fixes: 73563aa3d9 ("selftests/bpf: test_sockmap, print additional test options")
Fixes: 1ade9abadf ("bpf: test_sockmap, add options for msg_pop_data() helper")
Fixes: 463bac5f1c ("bpf, selftests: Add test for ktls with skb bpf ingress policy")
Fixes: e9dd904708 ("bpf: add tls support for testing in test_sockmap")
Fixes: 753fb2ee09 ("bpf: sockmap, add msg_peek tests to test_sockmap")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201203235440.2302137-2-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2020-12-03 15:54:40 -08:00 committed by Alexei Starovoitov
parent 3015b500ae
commit eceae70bde
1 changed files with 23 additions and 13 deletions
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36
tools/testing/selftests/bpf/test_sockmap.c
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@ -1273,6 +1273,16 @@ static char *test_to_str(int test)
return "unknown";
}
static void append_str(char *dst, const char *src, size_t dst_cap)
{
size_t avail = dst_cap - strlen(dst);
if (avail <= 1) /* just zero byte could be written */
return;
strncat(dst, src, avail - 1); /* strncat() adds + 1 for zero byte */
}
#define OPTSTRING 60
static void test_options(char *options)
{
@ -1281,42 +1291,42 @@ static void test_options(char *options)
memset(options, 0, OPTSTRING);
if (txmsg_pass)
strncat(options, "pass,", OPTSTRING);
append_str(options, "pass,", OPTSTRING);
if (txmsg_redir)
strncat(options, "redir,", OPTSTRING);
append_str(options, "redir,", OPTSTRING);
if (txmsg_drop)
strncat(options, "drop,", OPTSTRING);
append_str(options, "drop,", OPTSTRING);
if (txmsg_apply) {
snprintf(tstr, OPTSTRING, "apply %d,", txmsg_apply);
strncat(options, tstr, OPTSTRING);
append_str(options, tstr, OPTSTRING);
}
if (txmsg_cork) {
snprintf(tstr, OPTSTRING, "cork %d,", txmsg_cork);
strncat(options, tstr, OPTSTRING);
append_str(options, tstr, OPTSTRING);
}
if (txmsg_start) {
snprintf(tstr, OPTSTRING, "start %d,", txmsg_start);
strncat(options, tstr, OPTSTRING);
append_str(options, tstr, OPTSTRING);
}
if (txmsg_end) {
snprintf(tstr, OPTSTRING, "end %d,", txmsg_end);
strncat(options, tstr, OPTSTRING);
append_str(options, tstr, OPTSTRING);
}
if (txmsg_start_pop) {
snprintf(tstr, OPTSTRING, "pop (%d,%d),",
txmsg_start_pop, txmsg_start_pop + txmsg_pop);
strncat(options, tstr, OPTSTRING);
append_str(options, tstr, OPTSTRING);
}
if (txmsg_ingress)
strncat(options, "ingress,", OPTSTRING);
append_str(options, "ingress,", OPTSTRING);
if (txmsg_redir_skb)
strncat(options, "redir_skb,", OPTSTRING);
append_str(options, "redir_skb,", OPTSTRING);
if (txmsg_ktls_skb)
strncat(options, "ktls_skb,", OPTSTRING);
append_str(options, "ktls_skb,", OPTSTRING);
if (ktls)
strncat(options, "ktls,", OPTSTRING);
append_str(options, "ktls,", OPTSTRING);
if (peek_flag)
strncat(options, "peek,", OPTSTRING);
append_str(options, "peek,", OPTSTRING);
}
static int __test_exec(int cgrp, int test, struct sockmap_options *opt)