[Qemu-devel] [PATCH v2] block/vvfat: Fix crash when reporting error about too many files in directory

[Thomas Huth <thuth@redhat.com>]

When using the vvfat driver with a directory that contains too many files,
QEMU currently crashes. This can be triggered like this for example:

 mkdir /tmp/vvfattest
 cd /tmp/vvfattest
 for ((x=0;x<=513;x++)); do mkdir $x; done
 qemu-system-x86_64 -drive \
   file.driver=vvfat,file.dir=.,read-only=on,media=cdrom

Seems like read_directory() is changing the mapping->path variable. Make
sure we use the right pointer instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 block/vvfat.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index fc41841..f2e7d50 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -973,10 +973,10 @@ static int init_directories(BDRVVVFATState* s,
         mapping = array_get(&(s->mapping), i);
 
         if (mapping->mode & MODE_DIRECTORY) {
+            char *path = mapping->path;
             mapping->begin = cluster;
             if(read_directory(s, i)) {
-                error_setg(errp, "Could not read directory %s",
-                           mapping->path);
+                error_setg(errp, "Could not read directory %s", path);
                 return -1;
             }
             mapping = array_get(&(s->mapping), i);
-- 
1.8.3.1