On 6/11/25 14:41, Zhiguo Niu wrote: > Chao Yu <c...@kernel.org> 于2025年6月11日周三 14:07写道: >> >> On 6/11/25 00:08, Jaegeuk Kim wrote: >>> Hi Zhiguo, >>> >>> This patch causes CPU hang when running fsstress on >>> compressed/non-compressed >>> files. Please check. >> >> Oh, seems it may cause below deadlock: >> >> CPU0 >> process A >> - spin_lock(i_lock) >> software IRQ >> - end_io >> - igrab >> - spin_lock(i_lock) >> >> Thanks, > Hi Chao, > Thanks for pointing this out. > I have tested this patch locally about some basic cases before submission. > So it seems that should use the following method to solve this problem? > " store i_compress_algorithm/sbi in dic to avoid inode access?"
Zhiguo, Yeah, I guess so. Thanks, > thanks! > > >> >>> >>> On 06/05, Zhiguo Niu wrote: >>>> The decompress_io_ctx may be released asynchronously after >>>> I/O completion. If this file is deleted immediately after read, >>>> and the kworker of processing post_read_wq has not been executed yet >>>> due to high workloads, It is possible that the inode(f2fs_inode_info) >>>> is evicted and freed before it is used f2fs_free_dic. >>>> >>>> The UAF case as below: >>>> Thread A Thread B >>>> - f2fs_decompress_end_io >>>> - f2fs_put_dic >>>> - queue_work >>>> add free_dic work to post_read_wq >>>> - do_unlink >>>> - iput >>>> - evict >>>> - call_rcu >>>> This file is deleted after read. >>>> >>>> Thread C kworker to process >>>> post_read_wq >>>> - rcu_do_batch >>>> - f2fs_free_inode >>>> - kmem_cache_free >>>> inode is freed by rcu >>>> - process_scheduled_works >>>> - f2fs_late_free_dic >>>> - f2fs_free_dic >>>> - f2fs_release_decomp_mem >>>> read >>>> (dic->inode)->i_compress_algorithm >>>> >>>> This patch use igrab before f2fs_free_dic and iput after free the dic when >>>> dic free >>>> action is done by kworker. >>>> >>>> Cc: Daeho Jeong <daehoje...@google.com> >>>> Fixes: bff139b49d9f ("f2fs: handle decompress only post processing in >>>> softirq") >>>> Signed-off-by: Zhiguo Niu <zhiguo....@unisoc.com> >>>> Signed-off-by: Baocong Liu <baocong....@unisoc.com> >>>> --- >>>> v3: use igrab to replace __iget >>>> v2: use __iget/iput function >>>> --- >>>> fs/f2fs/compress.c | 14 +++++++++----- >>>> 1 file changed, 9 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c >>>> index b3c1df9..729ad16 100644 >>>> --- a/fs/f2fs/compress.c >>>> +++ b/fs/f2fs/compress.c >>>> @@ -1687,7 +1687,7 @@ static void f2fs_release_decomp_mem(struct >>>> decompress_io_ctx *dic, >>>> } >>>> >>>> static void f2fs_free_dic(struct decompress_io_ctx *dic, >>>> - bool bypass_destroy_callback); >>>> + bool bypass_destroy_callback, bool late_free); >>>> >>>> struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc) >>>> { >>>> @@ -1743,12 +1743,12 @@ struct decompress_io_ctx *f2fs_alloc_dic(struct >>>> compress_ctx *cc) >>>> return dic; >>>> >>>> out_free: >>>> - f2fs_free_dic(dic, true); >>>> + f2fs_free_dic(dic, true, false); >>>> return ERR_PTR(ret); >>>> } >>>> >>>> static void f2fs_free_dic(struct decompress_io_ctx *dic, >>>> - bool bypass_destroy_callback) >>>> + bool bypass_destroy_callback, bool late_free) >>>> { >>>> int i; >>>> >>>> @@ -1775,6 +1775,8 @@ static void f2fs_free_dic(struct decompress_io_ctx >>>> *dic, >>>> } >>>> >>>> page_array_free(dic->inode, dic->rpages, dic->nr_rpages); >>>> + if (late_free) >>>> + iput(dic->inode); >>>> kmem_cache_free(dic_entry_slab, dic); >>>> } >>>> >>>> @@ -1783,16 +1785,18 @@ static void f2fs_late_free_dic(struct work_struct >>>> *work) >>>> struct decompress_io_ctx *dic = >>>> container_of(work, struct decompress_io_ctx, free_work); >>>> >>>> - f2fs_free_dic(dic, false); >>>> + f2fs_free_dic(dic, false, true); >>>> } >>>> >>>> static void f2fs_put_dic(struct decompress_io_ctx *dic, bool in_task) >>>> { >>>> if (refcount_dec_and_test(&dic->refcnt)) { >>>> if (in_task) { >>>> - f2fs_free_dic(dic, false); >>>> + f2fs_free_dic(dic, false, false); >>>> } else { >>>> INIT_WORK(&dic->free_work, f2fs_late_free_dic); >>>> + /* use igrab to avoid inode is evicted simultaneously >>>> */ >>>> + f2fs_bug_on(F2FS_I_SB(dic->inode), >>>> !igrab(dic->inode)); >>>> queue_work(F2FS_I_SB(dic->inode)->post_read_wq, >>>> &dic->free_work); >>>> } >>>> -- >>>> 1.9.1 >> _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel