Mercurial > hg > nginx
comparison src/http/modules/ngx_http_memcached_module.c @ 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> |
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date | Mon, 06 Jul 2020 18:36:17 +0300 |
parents | 8b68d50090e4 |
children | d26db4f82d7d |
comparison
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deleted
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7673:c5840ca2063d | 7674:7731c710796f |
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483 u = ctx->request->upstream; | 483 u = ctx->request->upstream; |
484 b = &u->buffer; | 484 b = &u->buffer; |
485 | 485 |
486 if (u->length == (ssize_t) ctx->rest) { | 486 if (u->length == (ssize_t) ctx->rest) { |
487 | 487 |
488 if (ngx_strncmp(b->last, | 488 if (bytes > u->length |
489 || ngx_strncmp(b->last, | |
489 ngx_http_memcached_end + NGX_HTTP_MEMCACHED_END - ctx->rest, | 490 ngx_http_memcached_end + NGX_HTTP_MEMCACHED_END - ctx->rest, |
490 bytes) | 491 bytes) |
491 != 0) | 492 != 0) |
492 { | 493 { |
493 ngx_log_error(NGX_LOG_ERR, ctx->request->connection->log, 0, | 494 ngx_log_error(NGX_LOG_ERR, ctx->request->connection->log, 0, |
494 "memcached sent invalid trailer"); | 495 "memcached sent invalid trailer"); |
495 | 496 |
496 u->length = 0; | 497 u->length = 0; |
538 return NGX_OK; | 539 return NGX_OK; |
539 } | 540 } |
540 | 541 |
541 last += (size_t) (u->length - NGX_HTTP_MEMCACHED_END); | 542 last += (size_t) (u->length - NGX_HTTP_MEMCACHED_END); |
542 | 543 |
543 if (ngx_strncmp(last, ngx_http_memcached_end, b->last - last) != 0) { | 544 if (bytes > u->length |
545 || ngx_strncmp(last, ngx_http_memcached_end, b->last - last) != 0) | |
546 { | |
544 ngx_log_error(NGX_LOG_ERR, ctx->request->connection->log, 0, | 547 ngx_log_error(NGX_LOG_ERR, ctx->request->connection->log, 0, |
545 "memcached sent invalid trailer"); | 548 "memcached sent invalid trailer"); |
546 | 549 |
547 b->last = last; | 550 b->last = last; |
548 cl->buf->last = last; | 551 cl->buf->last = last; |