From 11e78cada516c1c04e0062c6c18fa14dc1559a21 Mon Sep 17 00:00:00 2001
From: Alexander Egorenkov <egorenar@linux.ibm.com>
Date: Tue, 19 Jan 2021 09:35:58 +0100
Subject: [PATCH] zdump: catch attempts to seek past end of file in zg_seek()
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Make zg_seek() more robust.

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
---
 zdump/zg.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/zdump/zg.c b/zdump/zg.c
index 378cbf9b..8f417936 100644
--- a/zdump/zg.c
+++ b/zdump/zg.c
@@ -280,6 +280,9 @@ off_t zg_seek(struct zg_fh *zg_fh, off_t off, enum zg_check check)
 {
 	off_t rc;
 
+	if (off >= zg_fh->sb.st_size)
+		ERR_EXIT("Trying to seek past file end \"%s\"", zg_fh->path);
+
 	rc = lseek(zg_fh->fh, off, SEEK_SET);
 	if (rc == -1 && check != ZG_CHECK_NONE)
 		ERR_EXIT_ERRNO("Could not seek \"%s\"", zg_fh->path);