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filefrag: Fix segfault on virtual fs

PATCH Applied Eric Sandeen 2 participants 2 messages Jun 26, 2012 – Jul 28, 2012

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Eric Sandeen

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#0 lore raw

PATCH 1/1 filefrag: Fix segfault on virtual fs

filefrag on a virtual fs like proc segfaults:

# filefrag /proc/filesystems 
Floating point exception

because stat.f_blocks is 0, so the calculation of cylgroups is 0, which leads to a divide by 0 when calculating expected extents.

Since it's only used for ext2 filesystems anyway, just move the calculation of expected under "if (is_ext2)" to fix this.

Reported-by Max Beikirch <[email protected]>
Signed-off-by Eric Sandeen <[email protected]>

---

misc/filefrag.c +6 -5
index 0583e91..b6e7d62 100644
@@ -365,11 +366,12 @@ static void frag_report(const char *filename)
 	else
 		printf("%s: %d extents found", filename, num_extents);
 	/* count, and thus expected, only set for indirect FIBMAP'd files */
-	expected = (count/((bs*8)-(fsinfo.f_files/8/cylgroups)-3))+1;
-	if (is_ext2 && expected && expected < num_extents)
-		printf(", perfection would be %d extent%s\n", expected,
-			(expected>1) ? "s" : "");
-	else
+	if (is_ext2) {
+		expected = (count/((bs*8)-(fsinfo.f_files/8/cylgroups)-3))+1;
+		if (expected && expected < num_extents)
+			printf(", perfection would be %d extent%s\n", expected,
+				(expected>1) ? "s" : "");
+	} else
 		fputc('\n', stdout);
 	close(fd);
 	once = 0;
Applied
#1 lore raw
Quoted 5 lines · Eric Sandeen

filefrag on a virtual fs like proc segfaults:

# filefrag /proc/filesystems 
Floating point exception
Quoted 8 lines

because stat.f_blocks is 0, so the calculation of cylgroups is 0, which leads to a divide by 0 when calculating expected extents.

Since it's only used for ext2 filesystems anyway, just move the calculation of expected under "if (is_ext2)" to fix this.

Reported-by Max Beikirch <[email protected]>
Signed-off-by Eric Sandeen <[email protected]>

Applied, thanks.

- Ted