[gfs2-utils] branch andyp-sparse updated: gfs2_edit: Don't return an invalid pointer from restore_block()

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

The following commit(s) were added to refs/heads/andyp-sparse by this push:
     new 465f107d gfs2_edit: Don't return an invalid pointer from restore_block()
465f107d is described below

commit 465f107d2844ee8a6d88c16d3575f6540aa361e4
Author: Andrew Price <anprice(a)redhat.com&gt;
AuthorDate: Wed Jun 16 08:12:51 2021 -0400

    gfs2_edit: Don't return an invalid pointer from restore_block()
    
    The restore buffer can be modified underneath us after the second call
    to restore_buf_next() so grab the blk and siglen values out of the
    buffer straight away instead of returning a pointer into it.
    
    Signed-off-by: Andrew Price <anprice(a)redhat.com&gt;
---
 gfs2/edit/savemeta.c | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/gfs2/edit/savemeta.c b/gfs2/edit/savemeta.c
index 22e5c71c..5ccc46a8 100644
--- a/gfs2/edit/savemeta.c
+++ b/gfs2/edit/savemeta.c
@@ -1215,36 +1215,33 @@ void savemeta(char *out_fn, int saveoption, int gziplevel)
 	exit(0);
 }
 
-static char *restore_block(struct metafd *mfd, struct saved_metablock **svbp)
+static char *restore_block(struct metafd *mfd, uint64_t *blk, uint16_t *siglen)
 {
 	struct saved_metablock *svb;
 	const char *errstr;
 	char *buf = NULL;
-	uint16_t siglen;
-	uint64_t blk;
 
 	svb = (struct saved_metablock *)(restore_buf_next(mfd, sizeof(*svb)));
 	if (svb == NULL)
 		goto nobuffer;
-	blk = be64_to_cpu(svb->blk);
-	siglen = be16_to_cpu(svb->siglen);
+	*blk = be64_to_cpu(svb->blk);
+	*siglen = be16_to_cpu(svb->siglen);
 
-	if (sbd.fssize && blk >= sbd.fssize) {
+	if (sbd.fssize && *blk >= sbd.fssize) {
 		fprintf(stderr, "Error: File system is too small to restore this
metadata.\n");
 		fprintf(stderr, "File system is %"PRIu64" blocks. Restore block =
%"PRIu64"\n",
-		        sbd.fssize, blk);
+		        sbd.fssize, *blk);
 		return NULL;
 	}
 
-	if (siglen > sbd.sd_bsize) {
+	if (*siglen > sbd.sd_bsize) {
 		fprintf(stderr, "Bad record length: %u for block %"PRIu64"
(0x%"PRIx64").\n",
-			siglen, blk, blk);
+			*siglen, *blk, *blk);
 		return NULL;
 	}
 
-	buf = restore_buf_next(mfd, siglen);
+	buf = restore_buf_next(mfd, *siglen);
 	if (buf != NULL) {
-		*svbp = svb;
 		return buf;
 	}
 nobuffer:
@@ -1289,20 +1286,17 @@ static int restore_data(int fd, struct metafd *mfd, int
printonly)
 	}
 
 	while (TRUE) {
-		struct saved_metablock *sm = NULL;
-		unsigned siglen;
-		uint64_t blk;
+		uint16_t siglen = 0;
+		uint64_t blk = 0;
 		char *bp;
 
-		bp = restore_block(mfd, &sm);
+		bp = restore_block(mfd, &blk, &siglen);
 		if (bp == NULL && mfd->eof)
 			break;
 		if (bp == NULL) {
 			free(buf);
 			return -1;
 		}
-		siglen = be16_to_cpu(sm->siglen);
-		blk = be64_to_cpu(sm->blk);
 		if (printonly) {
 			if (printonly > 1 && printonly == blk) {
 				display_block_type(bp, blk, TRUE);

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