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changeset 7094:c7d4017c8876

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Secure link: fixed stack buffer overflow. When secure link checksum has length of 23 or 24 bytes, decoded base64 value could occupy 17 or 18 bytes which is more than 16 bytes previously allocated for it on stack. The buffer overflow does not have any security implications since only one local variable was corrupted and this variable was not used in this case. The fix is to increase buffer size up to 18 bytes. Useless buffer size initialization is removed as well.
author Roman Arutyunyan <arut@nginx.com>
date Tue, 22 Aug 2017 21:22:59 +0300
parents acc2cddc7b45
children 0d45b4cf7c2e
files src/http/modules/ngx_http_secure_link_module.c
diffstat 1 files changed, 1 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/src/http/modules/ngx_http_secure_link_module.c
+++ b/src/http/modules/ngx_http_secure_link_module.c
@@ -107,7 +107,7 @@ ngx_http_secure_link_variable(ngx_http_r
     ngx_md5_t                     md5;
     ngx_http_secure_link_ctx_t   *ctx;
     ngx_http_secure_link_conf_t  *conf;
-    u_char                        hash_buf[16], md5_buf[16];
+    u_char                        hash_buf[18], md5_buf[16];
 
     conf = ngx_http_get_module_loc_conf(r, ngx_http_secure_link_module);
 
@@ -154,7 +154,6 @@ ngx_http_secure_link_variable(ngx_http_r
         goto not_found;
     }
 
-    hash.len = 16;
     hash.data = hash_buf;
 
     if (ngx_decode_base64url(&hash, &val) != NGX_OK) {