10587ba6bf
directory extents The directory extent list does not have to be a continuous list of data blocks. When GRUB tries to read a non-existant member of the list, grub_xfs_read_file() will return a block of zero'ed memory. Checking for a zero'ed magic number is sufficient to skip this non-existant data block. Prior to commit 07318ee7e (fs/xfs: Fix XFS directory extent parsing) this was handled as a subtle side effect of reading the (non-existant) tail data structure. Since the block was zero'ed the computation of the number of directory entries in the block would return 0 as well. (cherry picked from commit e0cd43f8a5486debeba17349abbb088001164d70)
50 lines
1.8 KiB
Diff
50 lines
1.8 KiB
Diff
From 426d43bdf15e3e65c9b2cc80aa4b416750c643c3 Mon Sep 17 00:00:00 2001
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From: openEuler Buildteam <buildteam@openEuler.org>
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Date: Sat, 11 May 2024 10:00:32 +0800
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Subject: [PATCH] Handle non-continuous data blocks in directory extents
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The directory extent list does not have to be a continuous list of data
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blocks. When GRUB tries to read a non-existant member of the list,
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grub_xfs_read_file() will return a block of zero'ed memory. Checking for
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a zero'ed magic number is sufficient to skip this non-existant data block.
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Prior to commit 07318ee7e (fs/xfs: Fix XFS directory extent parsing)
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this was handled as a subtle side effect of reading the (non-existant)
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tail data structure. Since the block was zero'ed the computation of the
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number of directory entries in the block would return 0 as well.
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---
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grub-core/fs/xfs.c | 10 ++++++++++
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1 file changed, 10 insertions(+)
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diff --git a/grub-core/fs/xfs.c b/grub-core/fs/xfs.c
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index 1ce5fa4..2a22e26 100644
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--- a/grub-core/fs/xfs.c
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+++ b/grub-core/fs/xfs.c
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@@ -904,6 +904,7 @@ grub_xfs_iterate_dir (grub_fshelp_node_t dir,
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int entries = -1;
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char *end = dirblock + dirblk_size;
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+ grub_uint32_t magic;
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numread = grub_xfs_read_file (dir, 0, 0,
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blk << dirblk_log2,
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@@ -914,6 +915,15 @@ grub_xfs_iterate_dir (grub_fshelp_node_t dir,
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return 0;
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}
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+ /*
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+ * If this data block isn't actually part of the extent list then
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+ * grub_xfs_read_file() returns a block of zeros. So, if the magic
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+ * number field is all zeros then this block should be skipped.
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+ */
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+ magic = *(grub_uint32_t *)(void *) dirblock;
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+ if (!magic)
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+ continue;
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+
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/*
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* Leaf and tail information are only in the data block if the number
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* of extents is 1.
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--
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2.33.0
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