Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D018047D93B; Thu, 20 Aug 2026 16:41:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787244076; cv=none; b=J1XPdlMCa80ehzyvaHxNtMEBzG0ZimlfnZJaSkeghU2Ws/jlC7q8olojhu7ZtJNMGVtRXA2JzxmpqJqH4rsi5XOG5jTStyawPZymJY1y6H+5FX9uDTBNdHcLDqfRSIYAND2crzDyioCa2B/PmLlO/3QlE0FPY0987gEwUS7MN5U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787244076; c=relaxed/simple; bh=BrytGzIEhOqtB46E5sG5EEfP0jeevAle97zAqXSiYgw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TPeB5COlweA1nzoBdWtXOCIC5RivmfTNBYKI20mb1DKyHZdKFXFRjaY491O12YjsXea4KqLaCwBl5/G9Vq1f4D2w2OsrGFXdcrdmP2Yn84f8NbLpy2++1og+HNQznD+AGjGx1YbGcx4VYb3xcwbCbou5L2OFnZqdokaG//DRrys= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LybliOgB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LybliOgB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 382461F000E9; Thu, 20 Aug 2026 16:41:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787244074; bh=Hn0YarH3YP9A0KyzAv0ssaN3ETBnR2Jc5zhkp7jNZ64=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LybliOgBSGLqkK0v/kq6XPWYBXKVFcnmu9AcVNRS4McE8y5SRXO3faIpAU9ijMFKy 4wePd8f1/skuMKBWcuLJpYjuw5L8+C2bw8vUuIzP48+6jXtNGixgPim6yzi1QWzh0P ilDLIEXb9d7BQCTg4J1xfJ29NpDOWuaZRBAg0avU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, JY , Chao Yu , Jaegeuk Kim , Jiucheng Xu Subject: [PATCH 5.10 042/235] f2fs: fix UAF issue in f2fs_merge_page_bio() Date: Thu, 20 Aug 2026 16:54:38 +0200 Message-ID: <20260820145217.708153172@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145216.426568665@linuxfoundation.org> References: <20260820145216.426568665@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chao Yu commit edf7e9040fc52c922db947f9c6c36f07377c52ea upstream. As JY reported in bugzilla [1], Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 pc : [0xffffffe51d249484] f2fs_is_cp_guaranteed+0x70/0x98 lr : [0xffffffe51d24adbc] f2fs_merge_page_bio+0x520/0x6d4 CPU: 3 UID: 0 PID: 6790 Comm: kworker/u16:3 Tainted: P B W OE 6.12.30-android16-5-maybe-dirty-4k #1 5f7701c9cbf727d1eebe77c89bbbeb3371e895e5 Tainted: [P]=PROPRIETARY_MODULE, [B]=BAD_PAGE, [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Workqueue: writeback wb_workfn (flush-254:49) Call trace: f2fs_is_cp_guaranteed+0x70/0x98 f2fs_inplace_write_data+0x174/0x2f4 f2fs_do_write_data_page+0x214/0x81c f2fs_write_single_data_page+0x28c/0x764 f2fs_write_data_pages+0x78c/0xce4 do_writepages+0xe8/0x2fc __writeback_single_inode+0x4c/0x4b4 writeback_sb_inodes+0x314/0x540 __writeback_inodes_wb+0xa4/0xf4 wb_writeback+0x160/0x448 wb_workfn+0x2f0/0x5dc process_scheduled_works+0x1c8/0x458 worker_thread+0x334/0x3f0 kthread+0x118/0x1ac ret_from_fork+0x10/0x20 [1] https://bugzilla.kernel.org/show_bug.cgi?id=220575 The panic was caused by UAF issue w/ below race condition: kworker - writepages - f2fs_write_cache_pages - f2fs_write_single_data_page - f2fs_do_write_data_page - f2fs_inplace_write_data - f2fs_merge_page_bio - add_inu_page : cache page #1 into bio & cache bio in io->bio_list - f2fs_write_single_data_page - f2fs_do_write_data_page - f2fs_inplace_write_data - f2fs_merge_page_bio - add_inu_page : cache page #2 into bio which is linked in io->bio_list write - f2fs_write_begin : write page #1 - f2fs_folio_wait_writeback - f2fs_submit_merged_ipu_write - f2fs_submit_write_bio : submit bio which inclues page #1 and #2 software IRQ - f2fs_write_end_io - fscrypt_free_bounce_page : freed bounced page which belongs to page #2 - inc_page_count( , WB_DATA_TYPE(data_folio), false) : data_folio points to fio->encrypted_page the bounced page can be freed before accessing it in f2fs_is_cp_guarantee() It can reproduce w/ below testcase: Run below script in shell #1: for ((i=1;i>0;i++)) do xfs_io -f /mnt/f2fs/enc/file \ -c "pwrite 0 32k" -c "fdatasync" Run below script in shell #2: for ((i=1;i>0;i++)) do xfs_io -f /mnt/f2fs/enc/file \ -c "pwrite 0 32k" -c "fdatasync" So, in f2fs_merge_page_bio(), let's avoid using fio->encrypted_page after commit page into internal ipu cache. Fixes: 0b20fcec8651 ("f2fs: cache global IPU bio") Reported-by: JY Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Jiucheng Xu Signed-off-by: Greg Kroah-Hartman --- fs/f2fs/data.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -968,7 +968,7 @@ alloc_new: if (fio->io_wbc) wbc_account_cgroup_owner(fio->io_wbc, fio->page, PAGE_SIZE); - inc_page_count(fio->sbi, WB_DATA_TYPE(page)); + inc_page_count(fio->sbi, WB_DATA_TYPE(fio->page)); *fio->last_block = fio->new_blkaddr; *fio->bio = bio;