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From 381bc5d98b2a8a65b1f559e31e67361a761aefee Mon Sep 17 00:00:00 2001
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From: Luis Henriques <lhenriques@suse.de>
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Date: Wed, 28 Oct 2020 15:55:50 +0000
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Subject: [PATCH 14/46] filefrag: handle invalid st_dev and blksize cases
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Content-Type: text/plain
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It is possible to crash filefrag with a "Floating point exception" in
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two different scenarios:
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1. When fstat() returns a device ID set to 0
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2. When FIGETBSZ ioctl returns a blocksize of 0
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In both scenarios a divide-by-zero will occur in frag_report() because
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variable blksize will be set to zero.
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I've managed to trigger this crash with an old CephFS kernel client,
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using xfstest generic/519. The first scenario has been fixed by kernel
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commit 75c9627efb72 ("ceph: map snapid to anonymous bdev ID"). The
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second scenario is also fixed with commit 8f97d1e99149 ("vfs: fix
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FIGETBSZ ioctl on an overlayfs file").
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However, it is desirable to handle these two scenarios gracefully by
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checking these conditions explicitly.
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Signed-off-by: Luis Henriques <lhenriques@suse.de>
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Signed-off-by: Lukas Czerner <lczerner@redhat.com>
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---
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misc/filefrag.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/misc/filefrag.c b/misc/filefrag.c
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index 032535f3..a5b9bfe9 100644
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--- a/misc/filefrag.c
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+++ b/misc/filefrag.c
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@@ -418,13 +418,13 @@ static int frag_report(const char *filename)
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goto out_close;
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}
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- if (last_device != st.st_dev) {
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+ if ((last_device != st.st_dev) || !st.st_dev) {
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if (fstatfs(fd, &fsinfo) < 0) {
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rc = -errno;
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perror("fstatfs");
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goto out_close;
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}
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- if (ioctl(fd, FIGETBSZ, &blksize) < 0)
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+ if ((ioctl(fd, FIGETBSZ, &blksize) < 0) || !blksize)
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blksize = fsinfo.f_bsize;
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if (verbose)
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printf("Filesystem type is: %lx\n",
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--
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2.35.1
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