2020-09-30 10:23:28

by Miaohe Lin

[permalink] [raw]
Subject: [PATCH] mm: 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 <[email protected]>
---
mm/swapfile.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 2b0c5fc1b0e6..4522b458a814 100644
--- 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:
--
2.19.1


2020-09-30 15:36:22

by Darrick J. Wong

[permalink] [raw]
Subject: Re: [PATCH] mm: Fix potential memory leak in sys_swapon

On Wed, Sep 30, 2020 at 06:18:03AM -0400, Miaohe Lin wrote:
> 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 <[email protected]>

LGTM,
Reviewed-by: Darrick J. Wong <[email protected]>

--D

> ---
> mm/swapfile.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 2b0c5fc1b0e6..4522b458a814 100644
> --- 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:
> --
> 2.19.1
>