On Wed, Oct 02, 2024 at 05:05:52PM +0200, Vegard Nossum wrote:
> From: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
>
> [ Upstream commit 6379b44cdcd67f5f5d986b73953e99700591edfa ]
>
> For error handling path in ubifs_symlink(), inode will be marked as
> bad first, then iput() is invoked. If inode->i_link is initialized by
> fscrypt_encrypt_symlink() in encryption scenario, inode->i_link won't
> be freed by callchain ubifs_free_inode -> fscrypt_free_inode in error
> handling path, because make_bad_inode() has changed 'inode->i_mode' as
> 'S_IFREG'.
> Following kmemleak is easy to be reproduced by injecting error in
> ubifs_jnl_update() when doing symlink in encryption scenario:
> unreferenced object 0xffff888103da3d98 (size 8):
> comm "ln", pid 1692, jiffies 4294914701 (age 12.045s)
> backtrace:
> kmemdup+0x32/0x70
> __fscrypt_encrypt_symlink+0xed/0x1c0
> ubifs_symlink+0x210/0x300 [ubifs]
> vfs_symlink+0x216/0x360
> do_symlinkat+0x11a/0x190
> do_syscall_64+0x3b/0xe0
> There are two ways fixing it:
> 1. Remove make_bad_inode() in error handling path. We can do that
> because ubifs_evict_inode() will do same processes for good
> symlink inode and bad symlink inode, for inode->i_nlink checking
> is before is_bad_inode().
> 2. Free inode->i_link before marking inode bad.
> Method 2 is picked, it has less influence, personally, I think.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 2c58d548f570 ("fscrypt: cache decrypted symlink target in ->i_link")
> Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
> Suggested-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> Signed-off-by: Richard Weinberger <richard@xxxxxx>
> (cherry picked from commit 6379b44cdcd67f5f5d986b73953e99700591edfa)
There isn't really a point to doing a cherry-pick -x if the information is
already included at the top. I am surprised that you're on cherry-picking from
the 6.10.y tree, though. Most stable patches are clean backports so it mostly
doesn't matter either way.
regards,
dan carpenter
