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commit 691505a803a7f223b2af621848d581259c61f77d upstream. A NULL-pointer dereference was reported in fedora bz#1762199 while reshaping a raid6 array after adding a fifth drive to an existing array. [ 47.343549] md/raid:md0: raid level 6 active with 3 out of 5 devices, algorithm 2 [ 47.804017] md0: detected capacity change from 0 to 7885289422848 [ 47.822083] Unable to handle kernel read from unreadable memory at virtual address 0000000000000000 ... [ 47.940477] CPU: 1 PID: 14210 Comm: md0_raid6 Tainted: G W 5.2.18-200.fc30.aarch64 #1 [ 47.949594] Hardware name: AMD Overdrive/Supercharger/To be filled by O.E.M., BIOS ROD1002C 04/08/2016 [ 47.958886] pstate: 00400085 (nzcv daIf +PAN -UAO) [ 47.963668] pc : __list_del_entry_valid+0x2c/0xa8 [ 47.968366] lr : ccp_tx_submit+0x84/0x168 [ccp] [ 47.972882] sp : ffff00001369b970 [ 47.976184] x29: ffff00001369b970 x28: ffff00001369bdb8 [ 47.981483] x27: 00000000ffffffff x26: ffff8003b758af70 [ 47.986782] x25: ffff8003b758b2d8 x24: ffff8003e6245818 [ 47.992080] x23: 0000000000000000 x22: ffff8003e62450c0 [ 47.997379] x21: ffff8003dfd6add8 x20: 0000000000000003 [ 48.002678] x19: ffff8003e6245100 x18: 0000000000000000 [ 48.007976] x17: 0000000000000000 x16: 0000000000000000 [ 48.013274] x15: 0000000000000000 x14: 0000000000000000 [ 48.018572] x13: ffff7e000ef83a00 x12: 0000000000000001 [ 48.023870] x11: ffff000010eff998 x10: 00000000000019a0 [ 48.029169] x9 : 0000000000000000 x8 : ffff8003e6245180 [ 48.034467] x7 : 0000000000000000 x6 : 000000000000003f [ 48.039766] x5 : 0000000000000040 x4 : ffff8003e0145080 [ 48.045064] x3 : dead000000000200 x2 : 0000000000000000 [ 48.050362] x1 : 0000000000000000 x0 : ffff8003e62450c0 [ 48.055660] Call trace: [ 48.058095] __list_del_entry_valid+0x2c/0xa8 [ 48.062442] ccp_tx_submit+0x84/0x168 [ccp] [ 48.066615] async_tx_submit+0x224/0x368 [async_tx] [ 48.071480] async_trigger_callback+0x68/0xfc [async_tx] [ 48.076784] ops_run_biofill+0x178/0x1e8 [raid456] [ 48.081566] raid_run_ops+0x248/0x818 [raid456] [ 48.086086] handle_stripe+0x864/0x1208 [raid456] [ 48.090781] handle_active_stripes.isra.0+0xb0/0x278 [raid456] [ 48.096604] raid5d+0x378/0x618 [raid456] [ 48.100602] md_thread+0xa0/0x150 [ 48.103905] kthread+0x104/0x130 [ 48.107122] ret_from_fork+0x10/0x18 [ 48.110686] Code: d2804003 f2fbd5a3 eb03003f 54000320 (f9400021) [ 48.116766] ---[ end trace 23f390a527f7ad77 ]--- ccp_tx_submit is passed a dma_async_tx_descriptor which is contained in a ccp_dma_desc and adds it to a ccp channel's pending list: list_del(&desc->entry); list_add_tail(&desc->entry, &chan->pending); The problem is that desc->entry may be uninitialized in the async_trigger_callback path where the descriptor was gotten from ccp_prep_dma_interrupt which got it from ccp_alloc_dma_desc which doesn't initialize the desc->entry list head. So, just initialize the list head to avoid the problem. Cc: <stable@vger.kernel.org> Reported-by: Sahaj Sarup <sahajsarup@gmail.com> Signed-off-by: Mark Salter <msalter@redhat.com> Acked-by: Gary R Hook <gary.hook@amd.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.