Mercurial > hg > nginx
comparison src/http/ngx_http_variables.c @ 8164:b71e69247483
Variables: avoid possible buffer overrun with some "$sent_http_*".
The existing logic to evaluate multi header "$sent_http_*" variables,
such as $sent_http_cache_control, as previously introduced in 1.23.0,
doesn't take into account that one or more elements can be cleared,
yet still present in a linked list, pointed to by the next field.
Such elements don't contribute to the resulting variable length, an
attempt to append a separator for them ends up in out of bounds write.
This is not possible with standard modules, though at least one third
party module is known to override multi header values this way, so it
makes sense to harden the logic.
The fix restores a generic boundary check.
author | Sergey Kandaurov <pluknet@nginx.com> |
---|---|
date | Mon, 01 May 2023 19:16:05 +0400 |
parents | cca4c8a715de |
children | 106b3832e7ef |
comparison
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8163:77d5c662f3d9 | 8164:b71e69247483 |
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826 static ngx_int_t | 826 static ngx_int_t |
827 ngx_http_variable_headers_internal(ngx_http_request_t *r, | 827 ngx_http_variable_headers_internal(ngx_http_request_t *r, |
828 ngx_http_variable_value_t *v, uintptr_t data, u_char sep) | 828 ngx_http_variable_value_t *v, uintptr_t data, u_char sep) |
829 { | 829 { |
830 size_t len; | 830 size_t len; |
831 u_char *p; | 831 u_char *p, *end; |
832 ngx_table_elt_t *h, *th; | 832 ngx_table_elt_t *h, *th; |
833 | 833 |
834 h = *(ngx_table_elt_t **) ((char *) r + data); | 834 h = *(ngx_table_elt_t **) ((char *) r + data); |
835 | 835 |
836 len = 0; | 836 len = 0; |
868 } | 868 } |
869 | 869 |
870 v->len = len; | 870 v->len = len; |
871 v->data = p; | 871 v->data = p; |
872 | 872 |
873 end = p + len; | |
874 | |
873 for (th = h; th; th = th->next) { | 875 for (th = h; th; th = th->next) { |
874 | 876 |
875 if (th->hash == 0) { | 877 if (th->hash == 0) { |
876 continue; | 878 continue; |
877 } | 879 } |
878 | 880 |
879 p = ngx_copy(p, th->value.data, th->value.len); | 881 p = ngx_copy(p, th->value.data, th->value.len); |
880 | 882 |
881 if (th->next == NULL) { | 883 if (p == end) { |
882 break; | 884 break; |
883 } | 885 } |
884 | 886 |
885 *p++ = sep; *p++ = ' '; | 887 *p++ = sep; *p++ = ' '; |
886 } | 888 } |