https://github.com/torvalds/linux
Revision 86d32f9a7c54ad74f4514d7fef7c847883207291 authored by Vasily Averin on 14 April 2020, 20:33:16 UTC, committed by Linus Torvalds on 16 April 2020, 17:10:50 UTC
If seq_file .next function does not change position index, read after some lseek can generate unexpected output: $ dd if=/proc/keys bs=1 # full usual output 0f6bfdf5 I--Q--- 2 perm 3f010000 1000 1000 user 4af2f79ab8848d0a: 740 1fb91b32 I--Q--- 3 perm 1f3f0000 1000 65534 keyring _uid.1000: 2 27589480 I--Q--- 1 perm 0b0b0000 0 0 user invocation_id: 16 2f33ab67 I--Q--- 152 perm 3f030000 0 0 keyring _ses: 2 33f1d8fa I--Q--- 4 perm 3f030000 1000 1000 keyring _ses: 1 3d427fda I--Q--- 2 perm 3f010000 1000 1000 user 69ec44aec7678e5a: 740 3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1 521+0 records in 521+0 records out 521 bytes copied, 0,00123769 s, 421 kB/s But a read after lseek in middle of last line results in the partial last line and then a repeat of the final line: $ dd if=/proc/keys bs=500 skip=1 dd: /proc/keys: cannot skip to specified offset g _uid_ses.1000: 1 3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1 0+1 records in 0+1 records out 97 bytes copied, 0,000135035 s, 718 kB/s and a read after lseek beyond end of file results in the last line being shown: $ dd if=/proc/keys bs=1000 skip=1 # read after lseek beyond end of file dd: /proc/keys: cannot skip to specified offset 3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1 0+1 records in 0+1 records out 76 bytes copied, 0,000119981 s, 633 kB/s See https://bugzilla.kernel.org/show_bug.cgi?id=206283 Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code ...") Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 0008633
Tip revision: 86d32f9a7c54ad74f4514d7fef7c847883207291 authored by Vasily Averin on 14 April 2020, 20:33:16 UTC
keys: Fix proc_keys_next to increase position index
keys: Fix proc_keys_next to increase position index
Tip revision: 86d32f9
test_string.c
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/string.h>
static __init int memset16_selftest(void)
{
unsigned i, j, k;
u16 v, *p;
p = kmalloc(256 * 2 * 2, GFP_KERNEL);
if (!p)
return -1;
for (i = 0; i < 256; i++) {
for (j = 0; j < 256; j++) {
memset(p, 0xa1, 256 * 2 * sizeof(v));
memset16(p + i, 0xb1b2, j);
for (k = 0; k < 512; k++) {
v = p[k];
if (k < i) {
if (v != 0xa1a1)
goto fail;
} else if (k < i + j) {
if (v != 0xb1b2)
goto fail;
} else {
if (v != 0xa1a1)
goto fail;
}
}
}
}
fail:
kfree(p);
if (i < 256)
return (i << 24) | (j << 16) | k | 0x8000;
return 0;
}
static __init int memset32_selftest(void)
{
unsigned i, j, k;
u32 v, *p;
p = kmalloc(256 * 2 * 4, GFP_KERNEL);
if (!p)
return -1;
for (i = 0; i < 256; i++) {
for (j = 0; j < 256; j++) {
memset(p, 0xa1, 256 * 2 * sizeof(v));
memset32(p + i, 0xb1b2b3b4, j);
for (k = 0; k < 512; k++) {
v = p[k];
if (k < i) {
if (v != 0xa1a1a1a1)
goto fail;
} else if (k < i + j) {
if (v != 0xb1b2b3b4)
goto fail;
} else {
if (v != 0xa1a1a1a1)
goto fail;
}
}
}
}
fail:
kfree(p);
if (i < 256)
return (i << 24) | (j << 16) | k | 0x8000;
return 0;
}
static __init int memset64_selftest(void)
{
unsigned i, j, k;
u64 v, *p;
p = kmalloc(256 * 2 * 8, GFP_KERNEL);
if (!p)
return -1;
for (i = 0; i < 256; i++) {
for (j = 0; j < 256; j++) {
memset(p, 0xa1, 256 * 2 * sizeof(v));
memset64(p + i, 0xb1b2b3b4b5b6b7b8ULL, j);
for (k = 0; k < 512; k++) {
v = p[k];
if (k < i) {
if (v != 0xa1a1a1a1a1a1a1a1ULL)
goto fail;
} else if (k < i + j) {
if (v != 0xb1b2b3b4b5b6b7b8ULL)
goto fail;
} else {
if (v != 0xa1a1a1a1a1a1a1a1ULL)
goto fail;
}
}
}
}
fail:
kfree(p);
if (i < 256)
return (i << 24) | (j << 16) | k | 0x8000;
return 0;
}
static __init int strchr_selftest(void)
{
const char *test_string = "abcdefghijkl";
const char *empty_string = "";
char *result;
int i;
for (i = 0; i < strlen(test_string) + 1; i++) {
result = strchr(test_string, test_string[i]);
if (result - test_string != i)
return i + 'a';
}
result = strchr(empty_string, '\0');
if (result != empty_string)
return 0x101;
result = strchr(empty_string, 'a');
if (result)
return 0x102;
result = strchr(test_string, 'z');
if (result)
return 0x103;
return 0;
}
static __init int strnchr_selftest(void)
{
const char *test_string = "abcdefghijkl";
const char *empty_string = "";
char *result;
int i, j;
for (i = 0; i < strlen(test_string) + 1; i++) {
for (j = 0; j < strlen(test_string) + 2; j++) {
result = strnchr(test_string, j, test_string[i]);
if (j <= i) {
if (!result)
continue;
return ((i + 'a') << 8) | j;
}
if (result - test_string != i)
return ((i + 'a') << 8) | j;
}
}
result = strnchr(empty_string, 0, '\0');
if (result)
return 0x10001;
result = strnchr(empty_string, 1, '\0');
if (result != empty_string)
return 0x10002;
result = strnchr(empty_string, 1, 'a');
if (result)
return 0x10003;
result = strnchr(NULL, 0, '\0');
if (result)
return 0x10004;
return 0;
}
static __init int string_selftest_init(void)
{
int test, subtest;
test = 1;
subtest = memset16_selftest();
if (subtest)
goto fail;
test = 2;
subtest = memset32_selftest();
if (subtest)
goto fail;
test = 3;
subtest = memset64_selftest();
if (subtest)
goto fail;
test = 4;
subtest = strchr_selftest();
if (subtest)
goto fail;
test = 5;
subtest = strnchr_selftest();
if (subtest)
goto fail;
pr_info("String selftests succeeded\n");
return 0;
fail:
pr_crit("String selftest failure %d.%08x\n", test, subtest);
return 0;
}
module_init(string_selftest_init);
MODULE_LICENSE("GPL v2");
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