[gfs2-utils] 17/38: gfs2_edit: Fix unaligned access in restore_init()

[git repository hosting]

This is an automated email from the git hooks/post-receive script.

andyp pushed a commit to branch RHEL7
in repository gfs2-utils.

commit 0fa27cdd64946c49823669e7ab77d8a06d9a00b9
Author: Andrew Price 
Date:   Wed Nov 9 18:27:12 2016 +0000

gfs2_edit: Fix unaligned access in restore_init()

Scanning this buffer byte-by-byte using casts results in a quick bus
    error on sparc64. Avoid this by using a memcpy. This function only runs
    once at the beginning of a restoremeta and in most cases the loop will
    only execute once so this adds very little overhead.

Reported-By: Valentin Vidic 
    Signed-off-by: Andrew Price 
---
 gfs2/edit/savemeta.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/gfs2/edit/savemeta.c b/gfs2/edit/savemeta.c
index c9b51e9..ac2dd9f 100644
--- a/gfs2/edit/savemeta.c
+++ b/gfs2/edit/savemeta.c
@@ -924,8 +924,7 @@ static off_t restore_init(gzFile gzfd, struct savemeta_header *smh)
    size_t rs;
    char buf[256];
    off_t startpos = 0;
-	struct saved_metablock *svb;
-	struct gfs2_meta_header *sbmh;
+	struct gfs2_meta_header sbmh;

err = read_header(gzfd, smh);
    if (err < 0) {
@@ -943,14 +942,15 @@ static off_t restore_init(gzFile gzfd, struct savemeta_header *smh)
    	exit(1);
    }
    /* Scan for the beginning of the file body. Required to support old formats(?). */
-	for (i = 0; i < (256 - sizeof(*svb) - sizeof(*sbmh)); i++) {
-		svb = (struct saved_metablock *)&buf[i];
-		sbmh = (struct gfs2_meta_header *)svb->buf;
-		if (sbmh->mh_magic == cpu_to_be32(GFS2_MAGIC) &&
-		     sbmh->mh_type == cpu_to_be32(GFS2_METATYPE_SB))
+	for (i = 0; i < (256 - sizeof(struct saved_metablock) - sizeof(sbmh)); i++) {
+		off_t off = i + sizeof(struct saved_metablock);
+
+		memcpy(&sbmh, &buf[off], sizeof(sbmh));
+		if (sbmh.mh_magic == cpu_to_be32(GFS2_MAGIC) &&
+		     sbmh.mh_type == cpu_to_be32(GFS2_METATYPE_SB))
    		break;
    }
-	if (i == (sizeof(buf) - sizeof(*svb) - sizeof(*sbmh)))
+	if (i == (sizeof(buf) - sizeof(struct saved_metablock) - sizeof(sbmh)))
    	i = 0;
    return startpos + i; /* File offset of saved sb */
 }