When trying to create a file in the full root directory of a FAT32 filesystem a NULL dereference can be observed.
When the root directory of a FAT16 filesystem is full fill_dir_slot() must return -1 to signal that a new directory entry could not be allocated.
Fixes: cd2d727fff7e ("fs: fat: allocate a new cluster for root directory of fat32") Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- fs/fat/fat_write.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index a2682b5f46..fc932df953 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -260,9 +260,8 @@ fill_dir_slot(fat_itr *itr, const char *l_name) flush_dir(itr);
/* allocate a cluster for more entries */ - if (!fat_itr_next(itr)) - if (!itr->dent && - (!itr->is_root || itr->fsdata->fatsize == 32) && + if (!fat_itr_next(itr) && !itr->dent) + if ((itr->is_root && itr->fsdata->fatsize != 32) || new_dir_table(itr)) return -1; } -- 2.29.2