From a683d652d334a546be9175b894f42dbd8e399536 Mon Sep 17 00:00:00 2001 From: Lee Schermerhorn Date: Fri, 21 Sep 2007 08:33:55 +0200 Subject: [PATCH] Panic in blk_rq_map_sg() from CCISS driver New scatter/gather list chaining [sg_next()] treats 'page' member of struct scatterlist with low bit set [0x01] as a chain pointer to another struct scatterlist [array]. The CCISS driver request function passes an uninitialized, temporary, on-stack scatterlist array to blk_rq_map_sq(). sg_next() interprets random data on the stack as a chain pointer and eventually tries to de-reference an invalid pointer, resulting in: [] blk_rq_map_sg+0x70/0x170 PGD 6090c3067 PUD 0 Oops: 0000 [1] SMP last sysfs file: /block/cciss!c0d0/cciss!c0d0p1/dev CPU 6 Modules linked in: ehci_hcd ohci_hcd uhci_hcd Pid: 1, comm: init Not tainted 2.6.23-rc6-mm1 #3 RIP: 0010:[] [] blk_rq_map_sg+0x70/0x170 RSP: 0018:ffff81060901f768 EFLAGS: 00010206 RAX: 000000040b161000 RBX: ffff81060901f7d8 RCX: 000000040b162c00 RDX: 0000000000000000 RSI: ffff81060b13a260 RDI: ffff81060b139600 RBP: 0000000000001400 R08: 00000000fffffffe R09: 0000000000000400 R10: 0000000000000000 R11: 000000040b163000 R12: ffff810102fe0000 R13: 0000000000000001 R14: 0000000000000001 R15: 00001e0000000000 FS: 00000000026108f0(0063) GS:ffff810409000b80(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 000000010000001e CR3: 00000006090c6000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process init (pid: 1, threadinfo ffff81060901e000, task ffff810409020800) last branch before last exception/interrupt from [] blk_rq_map_sg+0x10a/0x170 to [] blk_rq_map_sg+0x70/0x170 Stack: 000000018068ea00 ffff810102fe0000 0000000000000000 ffff810011400000 0000000000000002 0000000000000000 ffff81040b172000 ffffffff803acd3d 0000000000003ec1 ffff8106090d5000 ffff8106090d5000 ffff810102fe0000 Call Trace: [] do_cciss_request+0x15d/0x4c0 [] new_slab+0x1c8/0x270 [] __slab_alloc+0x22d/0x470 [] mempool_alloc+0x4b/0x130 [] cfq_set_request+0xee/0x380 [] mempool_alloc+0x4b/0x130 [] get_request+0x168/0x360 [] rb_insert_color+0x8d/0x110 [] elv_rb_add+0x58/0x60 [] cfq_add_rq_rb+0x69/0xa0 [] elv_merged_request+0x5b/0x60 [] __make_request+0x23d/0x650 [] __slab_alloc+0x22d/0x470 [] generic_write_checks+0x140/0x190 [] generic_make_request+0x1c2/0x3a0 Kernel panic - not syncing: Attempted to kill init! This patch initializes the tmp_sg array to zeroes. Perhaps not the ultimate fix, but an effective work-around. I can now boot 23-rc6-mm1 on an HP Proliant x86_64 with CCISS boot disk. Signed-off-by: Lee Schermerhorn drivers/block/cciss.c | 1 + 1 file changed, 1 insertion(+) Signed-off-by: Jens Axboe diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c index 55c3237..2023d61 100644 --- a/drivers/block/cciss.c +++ b/drivers/block/cciss.c @@ -2570,6 +2570,7 @@ static void do_cciss_request(struct request_queue *q) (int)creq->nr_sectors); #endif /* CCISS_DEBUG */ + memset(tmp_sg, 0, sizeof(tmp_sg)); seg = blk_rq_map_sg(q, creq, tmp_sg); /* get the DMA records for the setup */