Commit c2057260 authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

Merge branch 'Fix offset when fault occurs in strncpy_from_kernel_nofault()' 

Alban Crequy says:

====================

Hi,

This is v2 of the fix & selftest previously sent at:
https://lore.kernel.org/linux-mm/20221108195211.214025-1-flaniel@linux.microsoft.com/



Changes v1 to v2:
- add 'cc:stable', 'Fixes:' and review/ack tags
- update commitmsg and fix my email
- rebase on bpf tree and tag for bpf tree

Thanks!
====================

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parents 5704bc7e 9cd09482

mm/maccess.c

+1 −1
Original line number Diff line number Diff line
@@ -97,7 +97,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count) 
	return src - unsafe_addr;

Efault:

	pagefault_enable();

	dst[-1] = '\0';

	dst[0] = '\0';

	return -EFAULT;

}

tools/testing/selftests/bpf/prog_tests/varlen.c

+7 −0
Original line number Diff line number Diff line
@@ -63,6 +63,13 @@ void test_varlen(void) 
	CHECK_VAL(data->total4, size1 + size2);

	CHECK(memcmp(data->payload4, exp_str, size1 + size2), "content_check",

	      "doesn't match!\n");



	CHECK_VAL(bss->ret_bad_read, -EFAULT);

	CHECK_VAL(data->payload_bad[0], 0x42);

	CHECK_VAL(data->payload_bad[1], 0x42);

	CHECK_VAL(data->payload_bad[2], 0);

	CHECK_VAL(data->payload_bad[3], 0x42);

	CHECK_VAL(data->payload_bad[4], 0x42);

cleanup:

	test_varlen__destroy(skel);

}

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

+5 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ __u64 payload1_len1 = 0; 
__u64 payload1_len2 = 0;

__u64 total1 = 0;

char payload1[MAX_LEN + MAX_LEN] = {};

__u64 ret_bad_read = 0;



/* .data */

int payload2_len1 = -1;
@@ -36,6 +37,8 @@ int payload4_len2 = -1; 
int total4= -1;

char payload4[MAX_LEN + MAX_LEN] = { 1 };



char payload_bad[5] = { 0x42, 0x42, 0x42, 0x42, 0x42 };



SEC("raw_tp/sys_enter")

int handler64_unsigned(void *regs)

{
@@ -61,6 +64,8 @@ int handler64_unsigned(void *regs) 


	total1 = payload - (void *)payload1;



	ret_bad_read = bpf_probe_read_kernel_str(payload_bad + 2, 1, (void *) -1);



	return 0;

}