[gfs2-utils] 18/38: gfs2_edit: Fix unaligned accesses due to saved_metablock size

[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 f49411b143528300b6d19f390b1f68ea92716e9b
Author: Andrew Price 
Date:   Thu Nov 10 00:08:44 2016 +0000

gfs2_edit: Fix unaligned accesses due to saved_metablock size

Each saved block is prefixed by a saved_metablock structure that holds
    its block number and data length. Unfortunately this structure is 10
    bytes in size, which means that storing the metadata header in memory
    immediately following it causes accesses to the header fields to be
    unaligned. This causes testsuite failures on sparc64. Instead, on
    restore, use a separate buffer for the block data to ensure aligned
    accesses to those fields.

Reported-By: Valentin Vidic 
    Signed-off-by: Andrew Price 
---
 gfs2/edit/savemeta.c | 59 +++++++++++++++++++++++++---------------------------
 1 file changed, 28 insertions(+), 31 deletions(-)

diff --git a/gfs2/edit/savemeta.c b/gfs2/edit/savemeta.c
index ac2dd9f..f6b7ff0 100644
--- a/gfs2/edit/savemeta.c
+++ b/gfs2/edit/savemeta.c
@@ -44,7 +44,6 @@ struct savemeta_header {
 struct saved_metablock {
    uint64_t blk;
    uint16_t siglen; /* significant data length */
-	char buf[];
 /* This needs to be packed because old versions of gfs2_edit read and write the
    individual fields separately, so the hole after siglen must be eradicated
    before the struct reflects what's on disk. */
@@ -435,7 +434,7 @@ static int save_bh(struct metafd *mfd, struct gfs2_buffer_head *savebh, uint64_t
    }
    savedata->blk = cpu_to_be64(savebh->b_blocknr);
    savedata->siglen = cpu_to_be16(blklen);
-	memcpy(savedata->buf, savebh->b_data, blklen);
+	memcpy(savedata + 1, savebh->b_data, blklen);

if (savemetawrite(mfd, savedata, outsz) != outsz) {
    	fprintf(stderr, "write error: %s from %s:%d: block %lld (0x%llx)\n",
@@ -956,7 +955,7 @@ static off_t restore_init(gzFile gzfd, struct savemeta_header *smh)
 }

-static int restore_block(gzFile gzfd, struct saved_metablock *svb, uint16_t maxlen)
+static int restore_block(gzFile gzfd, struct saved_metablock *svb, char *buf, uint16_t maxlen)
 {
    int gzerr;
    int ret;
@@ -988,8 +987,8 @@ static int restore_block(gzFile gzfd, struct saved_metablock *svb, uint16_t maxl
    	return -1;
    }

-	if (maxlen) {
-		ret = gzread(gzfd, svb + 1, svb->siglen);
+	if (buf != NULL && maxlen != 0) {
+		ret = gzread(gzfd, buf, svb->siglen);
    	if (ret < svb->siglen) {
    		goto gzread_err;
    	}
@@ -1011,17 +1010,16 @@ gzread_err:
 static int restore_super(gzFile gzfd, off_t pos)
 {
    int ret;
-	struct saved_metablock *svb;
+	struct saved_metablock svb = {0};
    struct gfs2_buffer_head dummy_bh;
-	size_t len = sizeof(*svb) + sizeof(struct gfs2_sb);

-	svb = calloc(1, len);
-	if (svb == NULL) {
+	dummy_bh.b_data = calloc(1, sizeof(struct gfs2_sb));
+	if (dummy_bh.b_data == NULL) {
    	perror("Failed to restore super block");
    	exit(1);
    }
    gzseek(gzfd, pos, SEEK_SET);
-	ret = restore_block(gzfd, svb, sizeof(struct gfs2_sb));
+	ret = restore_block(gzfd, &svb, dummy_bh.b_data, sizeof(struct gfs2_sb));
    if (ret == 1) {
    	fprintf(stderr, "Reached end of file while restoring superblock\n");
    	goto err;
@@ -1029,7 +1027,6 @@ static int restore_super(gzFile gzfd, off_t pos)
    	goto err;
    }

-	dummy_bh.b_data = (char *)svb->buf;
    gfs2_sb_in(&sbd.sd_sb, &dummy_bh);
    sbd1 = (struct gfs_sb *)&sbd.sd_sb;
    ret = check_sb(&sbd.sd_sb);
@@ -1040,11 +1037,11 @@ static int restore_super(gzFile gzfd, off_t pos)
    if (ret == 1)
    	sbd.gfs1 = 1;
    sbd.bsize = sbd.sd_sb.sb_bsize;
-	free(svb);
+	free(dummy_bh.b_data);
    printf("Block size is %uB\n", sbd.bsize);
    return 0;
 err:
-	free(svb);
+	free(dummy_bh.b_data);
    return -1;
 }

@@ -1056,7 +1053,7 @@ static int find_highest_block(gzFile gzfd, off_t pos, uint64_t fssize)

while (1) {
    	gzseek(gzfd, pos, SEEK_SET);
-		err = restore_block(gzfd, &svb, 0);
+		err = restore_block(gzfd, &svb, NULL, 0);
    	if (err == 1)
    		break;
    	if (err != 0)
@@ -1081,12 +1078,12 @@ static int find_highest_block(gzFile gzfd, off_t pos, uint64_t fssize)

static int restore_data(int fd, gzFile gzin_fd, off_t pos, int printonly)
 {
-	struct saved_metablock *savedata;
-	size_t insz = sizeof(*savedata) + sbd.bsize;
+	struct saved_metablock savedata = {0};
    uint64_t writes = 0;
+	char *buf;

-	savedata = calloc(1, insz);
-	if (savedata == NULL) {
+	buf = calloc(1, sbd.bsize);
+	if (buf == NULL) {
    	perror("Failed to restore data");
    	exit(1);
    }
@@ -1095,36 +1092,36 @@ static int restore_data(int fd, gzFile gzin_fd, off_t pos, int printonly)
    blks_saved = 0;
    while (TRUE) {
    	int err;
-		err = restore_block(gzin_fd, savedata, sbd.bsize);
+		err = restore_block(gzin_fd, &savedata, buf, sbd.bsize);
    	if (err == 1)
    		break;
    	if (err != 0) {
-			free(savedata);
+			free(buf);
    		return -1;
    	}

if (printonly) {
    		struct gfs2_buffer_head dummy_bh = {
-				.b_data = savedata->buf,
-				.b_blocknr = savedata->blk,
+				.b_data = buf,
+				.b_blocknr = savedata.blk,
    		};
-			if (printonly > 1 && printonly == savedata->blk) {
+			if (printonly > 1 && printonly == savedata.blk) {
    			display_block_type(&dummy_bh, TRUE);
    			display_gfs2(&dummy_bh);
    			break;
    		} else if (printonly == 1) {
-				print_gfs2("%"PRId64" (l=0x%x): ", blks_saved, savedata->siglen);
+				print_gfs2("%"PRId64" (l=0x%x): ", blks_saved, savedata.siglen);
    			display_block_type(&dummy_bh, TRUE);
    		}
    	} else {
-			warm_fuzzy_stuff(savedata->blk, FALSE);
-			memset(savedata->buf + savedata->siglen, 0, sbd.bsize - savedata->siglen);
-			if (pwrite(fd, savedata->buf, sbd.bsize, savedata->blk * sbd.bsize) != sbd.bsize) {
+			warm_fuzzy_stuff(savedata.blk, FALSE);
+			memset(buf + savedata.siglen, 0, sbd.bsize - savedata.siglen);
+			if (pwrite(fd, buf, sbd.bsize, savedata.blk * sbd.bsize) != sbd.bsize) {
    			fprintf(stderr, "write error: %s from %s:%d: block %lld (0x%llx)\n",
    				strerror(errno), __FUNCTION__, __LINE__,
-					(unsigned long long)savedata->blk,
-					(unsigned long long)savedata->blk);
-				free(savedata);
+					(unsigned long long)savedata.blk,
+					(unsigned long long)savedata.blk);
+				free(buf);
    			return -1;
    		}
    		writes++;
@@ -1135,7 +1132,7 @@ static int restore_data(int fd, gzFile gzin_fd, off_t pos, int printonly)
    }
    if (!printonly)
    	warm_fuzzy_stuff(sbd.fssize, 1);
-	free(savedata);
+	free(buf);
    return 0;
 }