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 <amjadsharaf...@gmail.com>
---
block/vvfat.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/block/vvfat.c b/block/vvfat.c
index b63ac5d045..d2b879705e 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1360,15 +1360,17 @@ static int open_file(BDRVVVFATState* s,mapping_t*
mapping)
{
if(!mapping)
return -1;
- if(!s->current_mapping ||
- strcmp(s->current_mapping->path,mapping->path)) {
+ if (s->current_mapping != mapping) {
/* open file */
int fd = qemu_open_old(mapping->path,
- O_RDONLY | O_BINARY | O_LARGEFILE);
- if(fd<0)
+ O_RDONLY | O_BINARY | O_LARGEFILE);
+ if (fd < 0) {
return -1;
+ }
vvfat_close_current_file(s);
+
s->current_fd = fd;
+ assert(s->current_fd);
s->current_mapping = mapping;
}
return 0;
--
2.45.2
