From: Phil Sutter <phil@nwl.cc>
Date: Thu, 1 Mar 2018 14:00:28 +0000 (+0100)
Subject: erec: Avoid passing negative offset to fseek()
X-Git-Tag: v0.8.3~12
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3570b6bc8b4f136d07121b28cd79b6356e8e969b;p=thirdparty%2Fnftables.git

erec: Avoid passing negative offset to fseek()

If the initial call to ftell() fails, variable orig_offset is set to -1.
Avoid passing this to fseek() later on.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---

diff --git a/src/erec.c b/src/erec.c
index 80806ffe..8de249de 100644
--- a/src/erec.c
+++ b/src/erec.c
@@ -121,7 +121,7 @@ void erec_print(struct output_ctx *octx, const struct error_record *erec,
 	char buf[1024] = {};
 	char *pbuf = NULL;
 	unsigned int i, end;
-	int l, ret;
+	int l;
 	off_t orig_offset = 0;
 	FILE *f = octx->output_fp;
 
@@ -136,12 +136,12 @@ void erec_print(struct output_ctx *octx, const struct error_record *erec,
 		break;
 	case INDESC_FILE:
 		orig_offset = ftell(indesc->fp);
-		fseek(indesc->fp, loc->line_offset, SEEK_SET);
-		ret = fread(buf, 1, sizeof(buf) - 1, indesc->fp);
-		if (ret > 0)
+		if (orig_offset >= 0 &&
+		    !fseek(indesc->fp, loc->line_offset, SEEK_SET) &&
+		    fread(buf, 1, sizeof(buf) - 1, indesc->fp) > 0 &&
+		    !fseek(indesc->fp, orig_offset, SEEK_SET))
 			*strchrnul(buf, '\n') = '\0';
 		line = buf;
-		fseek(indesc->fp, orig_offset, SEEK_SET);
 		break;
 	case INDESC_INTERNAL:
 	case INDESC_NETLINK: