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Message-Id: <200801270158.28875.m.kozlowski@tuxland.pl> Date: Sun, 27 Jan 2008 01:58:28 +0100 From: Mariusz Kozlowski <m.kozlowski@...land.pl> To: James Bottomley <James.Bottomley@...senpartnership.com> Cc: Nathan Lynch <ntl@...ox.com>, linux-scsi@...r.kernel.org, Matthew Wilcox <matthew@....cx>, linux-kernel@...r.kernel.org, FUJITA Tomonori <tomof@....org> Subject: Re: [PATCH] sym53c8xx: fix bad memset argument in sym_set_cam_result_error 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 <ntl@...ox.com> > > > --- > > > 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 <tomof@....org> > > 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 <fujita.tomonori@....ntt.co.jp> > > Signed-off-by: James Bottomley <James.Bottomley@...senPartnership.com> > > > > 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 > > This logic is wrong. There was a commit > (de25deb18016f66dcdede165d07654559bb332bc) that changed > scsi_cmnd.sense_buffer from a char [96] to a char *, which is actually Ah that makes sense now. I thought scsi_cmnd.sense_buffer was a pointer earlier as well hence my description above. Regards, Mariusz > what caused this to break. sizeof(char [96]) is 96 and for some reason > in C &x->y == &x->y[0] if char y[something]. > > > 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. > > James -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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