Hi Greg, The following patch commit a41537e69b4aa43f0fea02498c2595a81267383b ext4: prevent bugon on race between write/fcntl fix CVE-2014-8086 in upstream kernel. I wish you could merge this fix into stable 3.10. Since refactoring in ext4, the sending patch is quite different from the patch in upstream kernel. Since ext4_file_dio_write() is not moved into ext4_file_write() (commit 8ad2850f), we should adjust 'overwrite' in ext4_file_write() to apply iocb->private which is initialized in upper function. Seems initializing iocb->private again is acceptable, but is not good for readability. From: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> commit a41537e69b4aa43f0fea02498c2595a81267383b upstream. O_DIRECT flags can be toggeled via fcntl(F_SETFL). But this value checked twice inside ext4_file_write_iter() and __generic_file_write() which result in BUG_ON inside ext4_direct_IO. Let's initialize iocb->private unconditionally. TESTCASE: xfstest:generic/036 https://patchwork.ozlabs.org/patch/402445/ #TYPICAL STACK TRACE: kernel BUG at fs/ext4/inode.c:2960! invalid opcode: 0000 [#1] SMP Modules linked in: brd iTCO_wdt lpc_ich mfd_core igb ptp dm_mirror dm_region_hash dm_log dm_mod CPU: 6 PID: 5505 Comm: aio-dio-fcntl-r Not tainted 3.17.0-rc2-00176-gff5c017 #161 Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.99.99.x028.061320111235 06/13/2011 task: ffff88080e95a7c0 ti: ffff88080f908000 task.ti: ffff88080f908000 RIP: 0010:[<ffffffff811fabf2>] [<ffffffff811fabf2>] ext4_direct_IO+0x162/0x3d0 RSP: 0018:ffff88080f90bb58 EFLAGS: 00010246 RAX: 0000000000000400 RBX: ffff88080fdb2a28 RCX: 00000000a802c818 RDX: 0000040000080000 RSI: ffff88080d8aeb80 RDI: 0000000000000001 RBP: ffff88080f90bbc8 R08: 0000000000000000 R09: 0000000000001581 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88080d8aeb80 R13: ffff88080f90bbf8 R14: ffff88080fdb28c8 R15: ffff88080fdb2a28 FS: 00007f23b2055700(0000) GS:ffff880818400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f23b2045000 CR3: 000000080cedf000 CR4: 00000000000407e0 Stack: ffff88080f90bb98 0000000000000000 7ffffffffffffffe ffff88080fdb2c30 0000000000000200 0000000000000200 0000000000000001 0000000000000200 ffff88080f90bbc8 ffff88080fdb2c30 ffff88080f90be08 0000000000000200 Call Trace: [<ffffffff8112ca9d>] generic_file_direct_write+0xed/0x180 [<ffffffff8112f2b2>] __generic_file_write_iter+0x222/0x370 [<ffffffff811f495b>] ext4_file_write_iter+0x34b/0x400 [<ffffffff811bd709>] ? aio_run_iocb+0x239/0x410 [<ffffffff811bd709>] ? aio_run_iocb+0x239/0x410 [<ffffffff810990e5>] ? local_clock+0x25/0x30 [<ffffffff810abd94>] ? __lock_acquire+0x274/0x700 [<ffffffff811f4610>] ? ext4_unwritten_wait+0xb0/0xb0 [<ffffffff811bd756>] aio_run_iocb+0x286/0x410 [<ffffffff810990e5>] ? local_clock+0x25/0x30 [<ffffffff810ac359>] ? lock_release_holdtime+0x29/0x190 [<ffffffff811bc05b>] ? lookup_ioctx+0x4b/0xf0 [<ffffffff811bde3b>] do_io_submit+0x55b/0x740 [<ffffffff811bdcaa>] ? do_io_submit+0x3ca/0x740 [<ffffffff811be030>] SyS_io_submit+0x10/0x20 [<ffffffff815ce192>] system_call_fastpath+0x16/0x1b Code: 01 48 8b 80 f0 01 00 00 48 8b 18 49 8b 45 10 0f 85 f1 01 00 00 48 03 45 c8 48 3b 43 48 0f 8f e3 01 00 00 49 83 7c 24 18 00 75 04 <0f> 0b eb fe f0 ff 83 ec 01 00 00 49 8b 44 24 18 8b 00 85 c0 89 RIP [<ffffffff811fabf2>] ext4_direct_IO+0x162/0x3d0 RSP <ffff88080f90bb58> Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> [hujianyang: Backported to 3.10 - Move initialization of iocb->private to ext4_file_write() as we don't have ext4_file_write_iter(), which is introduced by commit 9b884164. - Adjust context to make 'overwrite' changes apply to ext4_file_dio_write() as ext4_file_dio_write() is not move into ext4_file_write()] Signed-off-by: hujianyang <hujianyang@xxxxxxxxxx> --- fs/ext4/file.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 4635788..ec9770f 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -100,7 +100,7 @@ ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov, struct blk_plug plug; int unaligned_aio = 0; ssize_t ret; - int overwrite = 0; + int *overwrite = iocb->private; size_t length = iov_length(iov, nr_segs); if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) && @@ -118,8 +118,6 @@ ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov, mutex_lock(&inode->i_mutex); blk_start_plug(&plug); - iocb->private = &overwrite; - /* check whether we do a DIO overwrite or not */ if (ext4_should_dioread_nolock(inode) && !unaligned_aio && !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) { @@ -143,7 +141,7 @@ ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov, * So we should check these two conditions. */ if (err == len && (map.m_flags & EXT4_MAP_MAPPED)) - overwrite = 1; + *overwrite = 1; } ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); @@ -170,6 +168,7 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov, { struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret; + int overwrite = 0; /* * If we have encountered a bitmap-format file, the size limit @@ -190,6 +189,7 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov, } } + iocb->private = &overwrite; if (unlikely(iocb->ki_filp->f_flags & O_DIRECT)) ret = ext4_file_dio_write(iocb, iov, nr_segs, pos); else -- 1.6.0.2 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
