From 5eed3db336506b529b927ba221fe0d836e5b8819 Mon Sep 17 00:00:00 2001 From: Amjad Alsharafi Date: Sat, 20 Jul 2024 18:13:33 +0800 Subject: [PATCH] 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 Message-ID: <1f3ea115779abab62ba32c788073cdc99f9ad5dd.1721470238.git.amjadsharafi10@gmail.com> [kwolf: Simplified the patch based on Amjad's analysis and input] Signed-off-by: Kevin Wolf --- block/vvfat.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/vvfat.c b/block/vvfat.c index e3a83fbc88..8ffe8b3b9b 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; }