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build_SYS_str_reasons: Fix a crash caused by overlong locales

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The 4 kB SPACE_SYS_STR_REASONS in crypto/err/err.c isn't enough for some locales.
The Russian locales consume 6856 bytes, Ukrainian even 7000.

build_SYS_str_reasons() contains an overflow check:

if (cnt > sizeof(strerror_pool))
    cnt = sizeof(strerror_pool);

But since commit 9f15e5b911 it no longer
works as cnt is incremented once more after the condition.

cnt greater than sizeof(strerror_pool) results in an unbounded
OPENSSL_strlcpy() in openssl_strerror_r(), eventually causing a crash.

When the first received error string was empty or contained only
spaces, cur would move in front of the start of the strerror_pool.

Also don't call openssl_strerror_r when the pool is full.

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/8966)
This commit is contained in:
Vitezslav Cizek 2019-06-04 13:24:59 +02:00 committed by Tomas Mraz
parent d4f63f1c39
commit fac9200a88
1 changed files with 9 additions and 7 deletions
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16
crypto/err/err.c
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@ -188,8 +188,8 @@ static ERR_STRING_DATA *int_err_get_item(const ERR_STRING_DATA *d)
}
#ifndef OPENSSL_NO_ERR
/* A measurement on Linux 2018-11-21 showed about 3.5kib */
# define SPACE_SYS_STR_REASONS 4 * 1024
/* 2019-05-21: Russian and Ukrainian locales on Linux require more than 6,5 kB */
# define SPACE_SYS_STR_REASONS 8 * 1024
# define NUM_SYS_STR_REASONS 127
static ERR_STRING_DATA SYS_str_reasons[NUM_SYS_STR_REASONS + 1];
@ -223,21 +223,23 @@ static void build_SYS_str_reasons(void)
ERR_STRING_DATA *str = &SYS_str_reasons[i - 1];
str->error = ERR_PACK(ERR_LIB_SYS, 0, i);
if (str->string == NULL) {
/*
* If we have used up all the space in strerror_pool,
* there's no point in calling openssl_strerror_r()
*/
if (str->string == NULL && cnt < sizeof(strerror_pool)) {
if (openssl_strerror_r(i, cur, sizeof(strerror_pool) - cnt)) {
size_t l = strlen(cur);
str->string = cur;
cnt += l;
if (cnt > sizeof(strerror_pool))
cnt = sizeof(strerror_pool);
cur += l;
/*
* VMS has an unusual quirk of adding spaces at the end of
* some (most? all?) messages. Lets trim them off.
* some (most? all?) messages. Lets trim them off.
*/
while (ossl_isspace(cur[-1])) {
while (cur > strerror_pool && ossl_isspace(cur[-1])) {
cur--;
cnt--;
}