On Wed, Jul 01, 2020 at 08:05:58PM -0700, Stephen Hemminger wrote:
> If cfgfile is give a line with comment character at the start
> of the line, it will dereference outside of the buffer.
>
> Detected with address sanitizer:
>
> SUMMARY: AddressSanitizer: stack-buffer-underflow
> lib/librte_cfgfile/rte_cfgfile.c:194 in rte_cfgfile_load_with_params
> Shadow bytes around the buggy address:
> 0x200fff79f6a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0x200fff79f6b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0x200fff79f6c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0x200fff79f6d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0x200fff79f6e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> =>0x200fff79f6f0: 00 00 00 00 f1 f1 f1[f1]00 00 00 00 00 00 00 00
> 0x200fff79f700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0x200fff79f710: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 0x200fff79f720: 04 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00
> 0x200fff79f730: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 f2
> 0x200fff79f740: f2 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00
> Shadow byte legend (one shadow byte represents 8 application bytes):
> Addressable: 00
> Partially addressable: 01 02 03 04 05 06 07
> Heap left redzone: fa
> Freed heap region: fd
> Stack left redzone: f1
> Stack mid redzone: f2
> Stack right redzone: f3
> Stack after return: f5
> Stack use after scope: f8
> Global redzone: f9
> Global init order: f6
> Poisoned by user: f7
> Container overflow: fc
> Array cookie: ac
> Intra object redzone: bb
> ASan internal: fe
> Left alloca redzone: ca
> Right alloca redzone: cb
> ==2189==ABORTING
>
> Fixes: a6a47ac9c2c9 ("cfgfile: rework load function")
> Cc: jacekx.piase...@intel.com
> CC: sta...@dpdk.org
> Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
> ---
> lib/librte_cfgfile/rte_cfgfile.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_cfgfile/rte_cfgfile.c
> b/lib/librte_cfgfile/rte_cfgfile.c
> index 714717dd9007..160d78826e7c 100644
> --- a/lib/librte_cfgfile/rte_cfgfile.c
> +++ b/lib/librte_cfgfile/rte_cfgfile.c
> @@ -191,7 +191,8 @@ rte_cfgfile_load_with_params(const char *filename, int
> flags,
> }
> /* skip parsing if comment character found */
> pos = memchr(buffer, params->comment_character, len);
> - if (pos != NULL && (*(pos-1) != '\\')) {
> + if (pos != NULL &&
> + (pos == buffer || *(pos-1) != '\\')) {
> *pos = '\0';
> len = pos - buffer;
> }
> --
Good catch by the tool.
Reviewed-by: Bruce Richardson <bruce.richard...@intel.com>
