mm/swapfile.c: fix potential memory leak in sys_swapon

If we failed to drain inode, we would forget to free the swap address
space allocated by init_swap_address_space() above.

Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lkml.kernel.org/r/20200930101803.53884-1-linmiaohe@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index b23090c..c4a6136 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3342,7 +3342,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
        error = inode_drain_writes(inode);
        if (error) {
                inode->i_flags &= ~S_SWAPFILE;
-               goto bad_swap_unlock_inode;
+               goto free_swap_address_space;
        }
 
        mutex_lock(&swapon_mutex);
@@ -3367,6 +3367,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 
        error = 0;
        goto out;
+free_swap_address_space:
+       exit_swap_address_space(p->type);
 bad_swap_unlock_inode:
        inode_unlock(inode);
 bad_swap: