Thank you, Jon. I am also happy to test. Nicolas and I are all too
familiar with this now!
-marta
On 2/15/24 14:51, Daniel Kiper wrote:
Adding Marta, Nicolas, Sebastian and Vladimir...
Jon, thank you for the patch!
Marta, Nicolas and Sebastian, may I ask you to run tests with this fix?
Daniel
On Sun, Feb 11, 2024 at 10:34:58AM -0500, Jon DeVree wrote:
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 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.
Fixes: 07318ee7e (fs/xfs: Fix XFS directory extent parsing)
Fixes:https://bugzilla.redhat.com/show_bug.cgi?id=2254370
Signed-off-by: Jon DeVree<n...@vault24.org>
---
grub-core/fs/xfs.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/grub-core/fs/xfs.c b/grub-core/fs/xfs.c
index bc2224dbb..a6cce9cfe 100644
--- a/grub-core/fs/xfs.c
+++ b/grub-core/fs/xfs.c
@@ -902,6 +902,7 @@ grub_xfs_iterate_dir (grub_fshelp_node_t dir,
grub_xfs_first_de(dir->data, dirblock);
int entries = -1;
char *end = dirblock + dirblk_size;
+ grub_uint32_t magic;
numread = grub_xfs_read_file (dir, 0, 0,
blk << dirblk_log2,
@@ -912,6 +913,15 @@ grub_xfs_iterate_dir (grub_fshelp_node_t dir,
return 0;
}
+ /*
+ * If this data block isn't actually part of the extent list then
+ * grub_xfs_read_file() returns a block of zeros. So if the magic
number
+ * field is all zeros then this block should be skipped.
+ */
+ magic = *(grub_uint32_t *)dirblock;
+ if (!magic)
+ continue;
+
/*
* Leaf and tail information are only in the data block if the
number
* of extents is 1.
--
2.43.0
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