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| author | Amjad Alsharafi <amjadsharafi10@gmail.com> | 2024-07-20 18:13:33 +0800 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2024-08-06 20:12:39 +0200 |
| commit | 5eed3db336506b529b927ba221fe0d836e5b8819 (patch) | |
| tree | e870712ee9ba432c29d35b5f583a8b65bb81691d | |
| parent | f60a6f7e17bf2a2a0f0a08265ac9b077fce42858 (diff) | |
| download | qemu-5eed3db336506b529b927ba221fe0d836e5b8819.zip qemu-5eed3db336506b529b927ba221fe0d836e5b8819.tar.gz qemu-5eed3db336506b529b927ba221fe0d836e5b8819.tar.bz2 | |
vvfat: Fix reading files with non-continuous clusters
When reading with `read_cluster` we get the `mapping` with
`find_mapping_for_cluster` and then we call `open_file` for this
mapping.
The issue appear when its the same file, but a second cluster that is
not immediately after it, imagine clusters `500 -> 503`, this will give
us 2 mappings one has the range `500..501` and another `503..504`, both
point to the same file, but different offsets.
When we don't open the file since the path is the same, we won't assign
`s->current_mapping` and thus accessing way out of bound of the file.
From our example above, after `open_file` (that didn't open anything) we
will get the offset into the file with
`s->cluster_size*(cluster_num-s->current_mapping->begin)`, which will
give us `0x2000 * (504-500)`, which is out of bound for this mapping and
will produce some issues.
Signed-off-by: Amjad Alsharafi <amjadsharafi10@gmail.com>
Message-ID: <1f3ea115779abab62ba32c788073cdc99f9ad5dd.1721470238.git.amjadsharafi10@gmail.com>
[kwolf: Simplified the patch based on Amjad's analysis and input]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
| -rw-r--r-- | block/vvfat.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/block/vvfat.c b/block/vvfat.c index e3a83fb..8ffe8b3 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -1369,8 +1369,9 @@ static int open_file(BDRVVVFATState* s,mapping_t* mapping) return -1; vvfat_close_current_file(s); s->current_fd = fd; - s->current_mapping = mapping; } + + s->current_mapping = mapping; return 0; } |