Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755240AbYA0ATR (ORCPT ); Sat, 26 Jan 2008 19:19:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752789AbYA0ATF (ORCPT ); Sat, 26 Jan 2008 19:19:05 -0500 Received: from xdsl-664.zgora.dialog.net.pl ([81.168.226.152]:3492 "EHLO tuxland.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751725AbYA0ATD (ORCPT ); Sat, 26 Jan 2008 19:19:03 -0500 From: Mariusz Kozlowski To: Nathan Lynch Subject: Re: [PATCH] sym53c8xx: fix bad memset argument in sym_set_cam_result_error Date: Sun, 27 Jan 2008 01:18:58 +0100 User-Agent: KMail/1.9.7 Cc: linux-scsi@vger.kernel.org, Matthew Wilcox , linux-kernel@vger.kernel.org, FUJITA Tomonori , James Bottomley References: <20080126220730.GN14201@localdomain> In-Reply-To: <20080126220730.GN14201@localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200801270119.00429.m.kozlowski@tuxland.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5430 Lines: 119 Hello, > On a big powerpc box I got the following oops with 2.6.24-git2: > > sym0: <1010-66> rev 0x1 at pci 0000:d0:01.0 irq 215 > sym0: No NVRAM, ID 7, Fast-80, LVD, parity checking > sym0: SCSI BUS has been reset. > scsi0 : sym-2.2.3 > target0:0:8: FAST-40 WIDE SCSI 80.0 MB/s ST (25 ns, offset 31) > scsi 0:0:8:0: Direct-Access IBM ST318305LC C509 PQ: 0 > ANSI: 3 > target0:0:8: tagged command queuing enabled, command queue depth 16. > target0:0:8: Beginning Domain Validation > target0:0:8: asynchronous > target0:0:8: wide asynchronous > target0:0:8: FAST-80 WIDE SCSI 160.0 MB/s DT (12.5 ns, offset 31) > target0:0:8: FAST-80 WIDE SCSI 160.0 MB/s DT (12.5 ns, offset 31) > Unable to handle kernel paging request for data at address 0x00000000 > Faulting instruction address: 0xc000000000038460 > cpu 0x25: Vector: 300 (Data Access) at [c00000000f567840] > pc: c000000000038460: .memcpy+0x60/0x280 > lr: d000000000050280: .sym_set_cam_result_error+0xfc/0x1e0 [sym53c8xx] > sp: c00000000f567ac0 > msr: 8000000000009032 > dar: 0 > dsisr: 42000000 > current = 0xc000006d1e0af0a0 > paca = 0xc0000000004afc00 > pid = 0, comm = swapper > enter ? for help > [link register ] d000000000050280 > .sym_set_cam_result_error+0xfc/0x1e0 [sym53c8xx] > [c00000000f567ac0] c00000000f567b80 (unreliable) > [c00000000f567b80] d0000000000552b8 .sym_complete_error+0x12c/0x1bc [sym53c8xx] > [c00000000f567c20] d0000000000561a4 .sym_int_sir+0xaa4/0x1718 [sym53c8xx] > [c00000000f567d00] d000000000057e8c .sym_interrupt+0x4e4/0x6ec [sym53c8xx] > [c00000000f567dc0] d00000000004fdf4 .sym53c8xx_intr+0x6c/0xdc [sym53c8xx] > [c00000000f567e50] c0000000000a83e0 .handle_IRQ_event+0x7c/0xec > [c00000000f567ef0] c0000000000aa344 .handle_fasteoi_irq+0x130/0x1f0 > [c00000000f567f90] c00000000002a538 .call_handle_irq+0x1c/0x2c > [c000004d5e0b3a90] c00000000000c320 .do_IRQ+0x108/0x1d0 > [c000004d5e0b3b20] c000000000004790 hardware_interrupt_entry+0x18/0x1c > > The memset() in sym_set_cam_result_error() would appear to be trashing > the scsi_cmnd struct instead of clearing sense_buffer. > > Signed-off-by: Nathan Lynch > --- > drivers/scsi/sym53c8xx_2/sym_glue.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c > index 21e926d..e939f38 100644 > --- a/drivers/scsi/sym53c8xx_2/sym_glue.c > +++ b/drivers/scsi/sym53c8xx_2/sym_glue.c > @@ -207,7 +207,7 @@ void sym_set_cam_result_error(struct sym_hcb *np, struct sym_ccb *cp, int resid) > /* > * Bounce back the sense data to user. > */ > - memset(&cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); > + memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); > memcpy(cmd->sense_buffer, cp->sns_bbuf, > min(SCSI_SENSE_BUFFERSIZE, SYM_SNS_BBUF_LEN)); > #if 0 I was looking into it and found something interesting. What you see was just exposed by: commit b80ca4f7ee36c26d300c5a8f429e73372d153379 Author: FUJITA Tomonori Date: Sun Jan 13 15:46:13 2008 +0900 [SCSI] replace sizeof sense_buffer with This replaces sizeof sense_buffer with SCSI_SENSE_BUFFERSIZE in several LLDs. It's a preparation for the future changes to remove sense_buffer array in scsi_cmnd structure. Signed-off-by: FUJITA Tomonori Signed-off-by: James Bottomley But this is not a simple replace sizeof sense_buffer with SCSI_SENSE_BUFFERSIZE It has a side effect. Take a look a this portion of the commit: --- a/drivers/scsi/sym53c8xx_2/sym_glue.c +++ b/drivers/scsi/sym53c8xx_2/sym_glue.c @@ -207,10 +207,9 @@ void sym_set_cam_result_error(struct sym_hcb *np, struct sym_ccb *cp, int resid) /* * Bounce back the sense data to user. */ - memset(&cmd->sense_buffer, 0, sizeof(cmd->sense_buffer)); + memset(&cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); memcpy(cmd->sense_buffer, cp->sns_bbuf, - min(sizeof(cmd->sense_buffer), - (size_t)SYM_SNS_BBUF_LEN)); + min(SCSI_SENSE_BUFFERSIZE, SYM_SNS_BBUF_LEN)); Before the patch: 1) memset sets cmd->sense_buffer pointer value to zero (only 4 bytes which is wrong) 2) memcpy copies min(sizeof(cmd->sense_buffer), (size_t)SYM_SNS_BBUF_LEN)) which is equal to min(4, 32) so after this only first four bytes were copied from 32 bytes long cp->sns_bbuf into the sense_buffer After the patch: 1) memset zeroes 96 bytes of cmd structure starting at offset where sense_buffer in cmd is and results in an oops which you fixed 2) memcpy copies min(SCSI_SENSE_BUFFERSIZE, SYM_SNS_BBUF_LEN)) is equal to min(96, 32). cp->sns_bbuf is 32 bytes so I guess that's ok but that's different from the code before b80ca4f7 which was wrong (copied only 4 bytes) but 'worked'. Someone more experienced with that code should take a look at the logic of it. Regards, Mariusz -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/