From d8fa024ef1527a9aefbb52bedd70fa4449203488 Mon Sep 17 00:00:00 2001 From: Vladimir Khomutov Date: Wed, 29 Nov 2023 11:13:05 +0300 Subject: HTTP: uniform checks in ngx_http_alloc_large_header_buffer(). If URI is not fully parsed yet, some pointers are not set. As a result, the calculation of "new + (ptr - old)" expression is flawed. According to C11, 6.5.6 Additive operators, p.9: : When two pointers are subtracted, both shall point to elements : of the same array object, or one past the last element of the : array object Since "ptr" is not set, subtraction leads to undefined behaviour, because "ptr" and "old" are not in the same buffer (i.e. array objects). Prodded by GCC undefined behaviour sanitizer. --- src/http/ngx_http_request.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) (limited to 'src/http') diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c index 058d50286..21738ff4c 100644 --- a/src/http/ngx_http_request.c +++ b/src/http/ngx_http_request.c @@ -1718,14 +1718,23 @@ ngx_http_alloc_large_header_buffer(ngx_http_request_t *r, r->request_end = new + (r->request_end - old); } - r->method_end = new + (r->method_end - old); + if (r->method_end) { + r->method_end = new + (r->method_end - old); + } + + if (r->uri_start) { + r->uri_start = new + (r->uri_start - old); + } - r->uri_start = new + (r->uri_start - old); - r->uri_end = new + (r->uri_end - old); + if (r->uri_end) { + r->uri_end = new + (r->uri_end - old); + } if (r->schema_start) { r->schema_start = new + (r->schema_start - old); - r->schema_end = new + (r->schema_end - old); + if (r->schema_end) { + r->schema_end = new + (r->schema_end - old); + } } if (r->host_start) { @@ -1749,9 +1758,18 @@ ngx_http_alloc_large_header_buffer(ngx_http_request_t *r, } else { r->header_name_start = new; - r->header_name_end = new + (r->header_name_end - old); - r->header_start = new + (r->header_start - old); - r->header_end = new + (r->header_end - old); + + if (r->header_name_end) { + r->header_name_end = new + (r->header_name_end - old); + } + + if (r->header_start) { + r->header_start = new + (r->header_start - old); + } + + if (r->header_end) { + r->header_end = new + (r->header_end - old); + } } r->header_in = b; -- cgit