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openssl_strerror_r: Fix handling of GNU strerror_r

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GNU strerror_r may return either a pointer to a string that the function
stores in buf, or a pointer to some (immutable) static string in which case
buf is unused.

In such a case we need to set buf manually.

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8371)
This commit is contained in:
Vitezslav Cizek 2019-02-28 13:47:18 +01:00 committed by Matt Caswell
parent 68ad17e874
commit e3b35d2b29
1 changed files with 22 additions and 3 deletions
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25
crypto/o_str.c
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@ -223,7 +223,26 @@ int openssl_strerror_r(int errnum, char *buf, size_t buflen)
#if defined(_MSC_VER) && _MSC_VER>=1400
return !strerror_s(buf, buflen, errnum);
#elif defined(_GNU_SOURCE)
return strerror_r(errnum, buf, buflen) != NULL;
char *err;
/*
* GNU strerror_r may not actually set buf.
* It can return a pointer to some (immutable) static string in which case
* buf is left unused.
*/
err = strerror_r(errnum, buf, buflen);
if (err == NULL)
return 0;
/*
* If err is statically allocated, err != buf and we need to copy the data.
* If err points somewhere inside buf, OPENSSL_strlcpy can handle this,
* since src and dest are not annotated with __restrict and the function
* reads src byte for byte and writes to dest.
* If err == buf we do not have to copy anything.
*/
if (err != buf)
OPENSSL_strlcpy(buf, err, buflen);
return 1;
#elif (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || \
(defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600)
/*
@ -234,6 +253,7 @@ int openssl_strerror_r(int errnum, char *buf, size_t buflen)
return !strerror_r(errnum, buf, buflen);
#else
char *err;
/* Fall back to non-thread safe strerror()...its all we can do */
if (buflen < 2)
return 0;
@ -241,8 +261,7 @@ int openssl_strerror_r(int errnum, char *buf, size_t buflen)
/* Can this ever happen? */
if (err == NULL)
return 0;
strncpy(buf, err, buflen - 1);
buf[buflen - 1] = '\0';
OPENSSL_strlcpy(buf, err, buflen);
return 1;
#endif
}