| Message ID | 20140825130221.23329.86583.stgit@nfdev.cica.es |
|---|---|
| State | Not Applicable |
| Delegated to: | Pablo Neira |
| Headers | show |
On Mon, Aug 25, 2014 at 03:02:21PM +0200, Arturo Borrero Gonzalez wrote: > We must make sure the buffer contains a \0 in the last position, > to avoid printing trash by the last fprintf() call. snprintf already guarantees that the string is nul-terminated if there is enough room to add \0. ret = snprintf_cb(buf, bufsiz, obj, type, flags); if (ret < 0) goto out; if (ret >= NFT_SNPRINTF_BUFSIZ) { bufsiz = ret + 1; buf = malloc(bufsiz); if (buf == NULL) return -1; ret = snprintf_cb(buf, bufsiz, obj, type, flags); if (ret < 0) goto out; } ret = fprintf(fp, "%s", buf); I think we have guarantees that buf is always nul-terminated after the second try. Patch 2/2 looks good to enough to me since it already resolves the printed "garbage" at the end of the output issue. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/src/utils.c b/src/utils.c index 96c8bf2..8a7c521 100644 --- a/src/utils.c +++ b/src/utils.c @@ -189,6 +189,8 @@ int nft_fprintf(FILE *fp, void *obj, uint32_t type, uint32_t flags, size_t bufsiz = sizeof(_buf); int ret; + buf[0] = '\0'; + ret = snprintf_cb(buf, bufsiz, obj, type, flags); if (ret < 0) goto out; @@ -200,6 +202,8 @@ int nft_fprintf(FILE *fp, void *obj, uint32_t type, uint32_t flags, if (buf == NULL) return -1; + buf[0] = '\0'; + ret = snprintf_cb(buf, bufsiz, obj, type, flags); if (ret < 0) goto out;
We must make sure the buffer contains a \0 in the last position, to avoid printing trash by the last fprintf() call. This is needed because if the internal snprintf callback prints nothing, no \0 exists in the buffer. Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com> --- src/utils.c | 4 ++++ 1 file changed, 4 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html