Commit e5c13615 authored by Matt Caswell's avatar Matt Caswell
Browse files

Ensure we handle len == 0 in ERR_err_string_n 

If len == 0 in a call to ERR_error_string_n() then we can read beyond the
end of the buffer. Really applications should not be calling this function
with len == 0, but we shouldn't be letting it through either!

Thanks to Agostino Sarubbo for reporting this issue. Agostino's blog on
this issue is available here:
https://blogs.gentoo.org/ago/2016/10/14/openssl-libcrypto-stack-based-buffer-overflow-in-err_error_string_n-err-c/



Reviewed-by: default avatarRichard Levitte <levitte@openssl.org>
parent 3ff3ee7a

crypto/err/err.c

+3 −0
Original line number Diff line number Diff line
@@ -500,6 +500,9 @@ void ERR_error_string_n(unsigned long e, char *buf, size_t len) 
    const char *ls, *fs, *rs;

    unsigned long l, f, r;



    if (len == 0)

        return;



    l = ERR_GET_LIB(e);

    f = ERR_GET_FUNC(e);

    r = ERR_GET_REASON(e);