[PATCH] xfsprogs: Fix possible unallocated memory access in fiemap

[Lukas Czerner]

Currently we could access unallocated memory in fiemap because we're
using uninitialized variable 'fiemap' in fiemap_f(). In fact this has
been spotted on x390s machine where xfs_io would segfault.

The problem happens in the for cycle which seems to be intended to
compute the header item spacing. However at that point the fiemap
structure has just been allocated and does not contain any extents
yet, so it is entirely useless and it never actually worked.

This patch removes this dead code mentioned above which also fixes
the possible unallocated memory access.

Signed-off-by: Lukas Czerner <lczerner at redhat.com>
---
 io/fiemap.c |   40 +---------------------------------------
 1 files changed, 1 insertions(+), 39 deletions(-)

diff --git a/io/fiemap.c b/io/fiemap.c
index e32a416..e15bc61 100644
--- a/io/fiemap.c
+++ b/io/fiemap.c
@@ -49,19 +49,6 @@ fiemap_help(void)
 "\n"));
 }
 
-static int
-numlen(
-	__u64	val,
-	int	base)
-{
-	__u64	tmp;
-	int	len;
-
-	for (len = 0, tmp = val; tmp > 0; tmp = tmp/base)
-		len++;
-	return (len == 0 ? 1 : len);
-}
-
 static void
 print_verbose(
 	struct fiemap_extent	*extent,
@@ -215,37 +202,12 @@ fiemap_f(
 
 	printf("%s:\n", file->name);
 
-	if (vflag) {
-		for (i = 0; i < fiemap->fm_mapped_extents; i++) {
-			char			lbuf[32];
-			char			bbuf[32];
-			__u64			logical;
-			__u64			block;
-			__u64			len;
-			struct fiemap_extent	*extent;
-
-			extent = &fiemap->fm_extents[i];
-			logical = extent->fe_logical / blocksize;
-			len = extent->fe_length / blocksize;
-			block = extent->fe_physical / blocksize;
-
-			snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]", logical,
-				 logical + len - 1);
-			snprintf(bbuf, sizeof(bbuf), "%llu..%llu", block,
-				 block + len - 1);
-			foff_w = max(foff_w, strlen(lbuf));
-			boff_w = max(boff_w, strlen(bbuf));
-			tot_w = max(tot_w, numlen(len, 10));
-			flg_w = max(flg_w, numlen(extent->fe_flags, 16));
-			if (extent->fe_flags & FIEMAP_EXTENT_LAST)
-				break;
-		}
+	if (vflag)
 		printf("%4s: %-*s %-*s %*s %*s\n", _("EXT"),
 		       foff_w, _("FILE-OFFSET"),
 		       boff_w, _("BLOCK-RANGE"),
 		       tot_w, _("TOTAL"),
 		       flg_w, _("FLAGS"));
-	}
 
 	while (!last && ((cur_extent + 1) != max_extents)) {
 		if (max_extents)
-- 
1.7.7.6