On 2018/2/26 10:57, Yunlong Song wrote:
> In some platforms (such as arm), high memory is used, then the
> decrypting filename will cause panic, the reason see commit
> 569cf1876a32e574ba8a7fb825cd91bafd003882 ("f2fs crypto: allocate buffer
> for decrypting filename"):
>
> We got dentry pages from high_mem, and its address space directly goes into
> the
> decryption path via f2fs_fname_disk_to_usr.
> But, sg_init_one assumes the address is not from high_mem, so we can get this
> panic since it doesn't call kmap_high but kunmap_high is triggered at the
> end.
>
> kernel BUG at ../../../../../../kernel/mm/highmem.c:290!
> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> ...
> (kunmap_high+0xb0/0xb8) from [<c0114534>] (__kunmap_atomic+0xa0/0xa4)
> (__kunmap_atomic+0xa0/0xa4) from [<c035f028>]
> (blkcipher_walk_done+0x128/0x1ec)
> (blkcipher_walk_done+0x128/0x1ec) from [<c0366c24>]
> (crypto_cbc_decrypt+0xc0/0x170)
> (crypto_cbc_decrypt+0xc0/0x170) from [<c0367148>]
> (crypto_cts_decrypt+0xc0/0x114)
> (crypto_cts_decrypt+0xc0/0x114) from [<c035ea98>] (async_decrypt+0x40/0x48)
> (async_decrypt+0x40/0x48) from [<c032ca34>]
> (f2fs_fname_disk_to_usr+0x124/0x304)
> (f2fs_fname_disk_to_usr+0x124/0x304) from [<c03056fc>]
> (f2fs_fill_dentries+0xac/0x188)
> (f2fs_fill_dentries+0xac/0x188) from [<c03059c8>] (f2fs_readdir+0x1f0/0x300)
> (f2fs_readdir+0x1f0/0x300) from [<c0218054>] (vfs_readdir+0x90/0xb4)
> (vfs_readdir+0x90/0xb4) from [<c0218418>] (SyS_getdents64+0x64/0xcc)
> (SyS_getdents64+0x64/0xcc) from [<c0105ba0>] (ret_fast_syscall+0x0/0x30)
>
> Howerver, later patches:
> commit e06f86e61d7a67fe6e826010f57aa39c674f4b1b ("f2fs crypto: avoid
> unneeded memory allocation in ->readdir")
>
> reverts the codes, which causes panic again in arm, so let's add part of
> the old patch again for dentry page.
>
> Signed-off-by: Yunlong Song <yunlong.s...@huawei.com>
> ---
> fs/f2fs/dir.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index f00b5ed..23fff48 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -825,9 +825,15 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct
> f2fs_dentry_ptr *d,
> int save_len = fstr->len;
> int err;
>
> + de_name.name = kmemdup(d->filename[bit_pos],
How about using f2fs_kmalloc + memcpy here?
Thanks,
> + de_name.len, GFP_NOFS);
> + if (!de_name.name)
> + return -ENOMEM;
> +
> err = fscrypt_fname_disk_to_usr(d->inode,
> (u32)de->hash_code, 0,
> &de_name, fstr);
> + kfree(de_name.name);
> if (err)
> return err;
>
>
