57 lines
2.1 KiB
Diff
57 lines
2.1 KiB
Diff
From: =?UTF-8?q?Ernesto=20A=2E=20Fern=C3=A1ndez?=
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<ernesto.mnd.fernandez@gmail.com>
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Date: Thu, 23 Aug 2018 17:00:25 -0700
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Subject: hfsplus: fix NULL dereference in hfsplus_lookup()
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Origin: https://git.kernel.org/linus/a7ec7a4193a2eb3b5341243fc0b621c1ac9e4ec4
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An HFS+ filesystem can be mounted read-only without having a metadata
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directory, which is needed to support hardlinks. But if the catalog
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data is corrupted, a directory lookup may still find dentries claiming
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to be hardlinks.
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hfsplus_lookup() does check that ->hidden_dir is not NULL in such a
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situation, but mistakenly does so after dereferencing it for the first
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time. Reorder this check to prevent a crash.
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This happens when looking up corrupted catalog data (dentry) on a
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filesystem with no metadata directory (this could only ever happen on a
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read-only mount). Wen Xu sent the replication steps in detail to the
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fsdevel list: https://bugzilla.kernel.org/show_bug.cgi?id=200297
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Link: http://lkml.kernel.org/r/20180712215344.q44dyrhymm4ajkao@eaf
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Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
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Reported-by: Wen Xu <wen.xu@gatech.edu>
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Cc: Viacheslav Dubeyko <slava@dubeyko.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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fs/hfsplus/dir.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
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index c5a70f83dbe7..f37662675c3a 100644
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--- a/fs/hfsplus/dir.c
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+++ b/fs/hfsplus/dir.c
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@@ -77,13 +77,13 @@ static struct dentry *hfsplus_lookup(struct inode *dir, struct dentry *dentry,
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cpu_to_be32(HFSP_HARDLINK_TYPE) &&
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entry.file.user_info.fdCreator ==
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cpu_to_be32(HFSP_HFSPLUS_CREATOR) &&
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+ HFSPLUS_SB(sb)->hidden_dir &&
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(entry.file.create_date ==
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HFSPLUS_I(HFSPLUS_SB(sb)->hidden_dir)->
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create_date ||
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entry.file.create_date ==
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HFSPLUS_I(d_inode(sb->s_root))->
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- create_date) &&
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- HFSPLUS_SB(sb)->hidden_dir) {
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+ create_date)) {
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struct qstr str;
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char name[32];
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--
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2.19.0
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