From e3b35d2b29e9446af83fcaa534e67e7b04a60d7a Mon Sep 17 00:00:00 2001 From: Vitezslav Cizek Date: Thu, 28 Feb 2019 13:47:18 +0100 Subject: [PATCH] openssl_strerror_r: Fix handling of GNU strerror_r 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 Reviewed-by: Matt Caswell (Merged from https://github.com/openssl/openssl/pull/8371) --- crypto/o_str.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) diff --git a/crypto/o_str.c b/crypto/o_str.c index 02578dbf0d..3b271e745b 100644 --- a/crypto/o_str.c +++ b/crypto/o_str.c @@ -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 } -- 2.25.1