| Message ID | 47b12037459a0df1748dac7440c0f5030e5c3ef4.1647720651.git.chunkeey@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] ata: sata_dwc_460ex: Fix crash due to OOB write | expand |
On 3/20/22 05:11, Christian Lamparter wrote: > the driver uses libata's "tag" values from in various arrays. > Since the mentioned patch bumped the ATA_TAG_INTERNAL to 32, > the value of the SATA_DWC_QCMD_MAX needs to account for that. > > Otherwise ATA_TAG_INTERNAL usage cause similar crashes like > this as reported by Tice Rex on the OpenWrt Forum and > reproduced (with symbols) here: > > | BUG: Kernel NULL pointer dereference at 0x00000000 > | Faulting instruction address: 0xc03ed4b8 > | Oops: Kernel access of bad area, sig: 11 [#1] > | BE PAGE_SIZE=4K PowerPC 44x Platform > | CPU: 0 PID: 362 Comm: scsi_eh_1 Not tainted 5.4.163 #0 > | NIP: c03ed4b8 LR: c03d27e8 CTR: c03ed36c > | REGS: cfa59950 TRAP: 0300 Not tainted (5.4.163) > | MSR: 00021000 <CE,ME> CR: 42000222 XER: 00000000 > | DEAR: 00000000 ESR: 00000000 > | GPR00: c03d27e8 cfa59a08 cfa55fe0 00000000 0fa46bc0 [...] > | [..] > | NIP [c03ed4b8] sata_dwc_qc_issue+0x14c/0x254 > | LR [c03d27e8] ata_qc_issue+0x1c8/0x2dc > | Call Trace: > | [cfa59a08] [c003f4e0] __cancel_work_timer+0x124/0x194 (unreliable) > | [cfa59a78] [c03d27e8] ata_qc_issue+0x1c8/0x2dc > | [cfa59a98] [c03d2b3c] ata_exec_internal_sg+0x240/0x524 > | [cfa59b08] [c03d2e98] ata_exec_internal+0x78/0xe0 > | [cfa59b58] [c03d30fc] ata_read_log_page.part.38+0x1dc/0x204 > | [cfa59bc8] [c03d324c] ata_identify_page_supported+0x68/0x130 > | [...] > > This is because sata_dwc_dma_xfer_complete() NULLs the > dma_pending's next neighbour "chan" (a *dma_chan struct) in > this '32' case right here (line ~735): >> hsdevp->dma_pending[tag] = SATA_DWC_DMA_PENDING_NONE; > > Then the next time, a dma gets issued; dma_dwc_xfer_setup() passes > the NULL'd hsdevp->chan to the dmaengine_slave_config() which then > causes the crash. > > With this patch, SATA_DWC_QCMD_MAX is now set to ATA_MAX_QUEUE + 1. > This avoids the OOB. But please note, there was a worthwhile discussion > on what ATA_TAG_INTERNAL and ATA_MAX_QUEUE is. And why there should not > be a "fake" 33 command-long queue size. > > Ideally, the dw driver should account for the ATA_TAG_INTERNAL. > In Damien Le Moal's words: "... having looked at the driver, it > is a bigger change than just faking a 33rd "tag" that is in fact > not a command tag at all." > > Fixes: 28361c403683c ("libata: add extra internal command") > Cc: stable@kernel.org # 4.18+ > BugLink: https://github.com/openwrt/openwrt/issues/9505 > Signed-off-by: Christian Lamparter <chunkeey@gmail.com> Applied to for-5.18-fixes. Thanks !
diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c index bec33d781ae0..e3263e961045 100644 --- a/drivers/ata/sata_dwc_460ex.c +++ b/drivers/ata/sata_dwc_460ex.c @@ -137,7 +137,11 @@ struct sata_dwc_device { #endif }; -#define SATA_DWC_QCMD_MAX 32 +/* + * Allow one extra special slot for commands and DMA management + * to account for libata internal commands. + */ +#define SATA_DWC_QCMD_MAX (ATA_MAX_QUEUE + 1) struct sata_dwc_device_port { struct sata_dwc_device *hsdev;