Mercurial > hg > nginx
changeset 7674:7731c710796f
Memcached: protect from too long responses.
If a memcached response was followed by a correct trailer, and then
the NUL character followed by some extra data - this was accepted by
the trailer checking code. This in turn resulted in ctx->rest underflow
and caused negative size buffer on the next reading from the upstream,
followed by the "negative size buf in writer" alert.
Fix is to always check for too long responses, so a correct trailer cannot
be followed by extra data.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 06 Jul 2020 18:36:17 +0300 |
parents | c5840ca2063d |
children | 9afa45068b8f |
files | src/http/modules/ngx_http_memcached_module.c |
diffstat | 1 files changed, 6 insertions(+), 3 deletions(-) [+] |
line wrap: on
line diff
--- a/src/http/modules/ngx_http_memcached_module.c Fri Jul 03 16:16:47 2020 +0300 +++ b/src/http/modules/ngx_http_memcached_module.c Mon Jul 06 18:36:17 2020 +0300 @@ -485,10 +485,11 @@ if (u->length == (ssize_t) ctx->rest) { - if (ngx_strncmp(b->last, + if (bytes > u->length + || ngx_strncmp(b->last, ngx_http_memcached_end + NGX_HTTP_MEMCACHED_END - ctx->rest, bytes) - != 0) + != 0) { ngx_log_error(NGX_LOG_ERR, ctx->request->connection->log, 0, "memcached sent invalid trailer"); @@ -540,7 +541,9 @@ last += (size_t) (u->length - NGX_HTTP_MEMCACHED_END); - if (ngx_strncmp(last, ngx_http_memcached_end, b->last - last) != 0) { + if (bytes > u->length + || ngx_strncmp(last, ngx_http_memcached_end, b->last - last) != 0) + { ngx_log_error(NGX_LOG_ERR, ctx->request->connection->log, 0, "memcached sent invalid trailer");