On Fri, Mar 18, 2022 at 10:03:11AM +0100, 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 be bumped to 33. > > Otherwise ATA_TAG_INTERNAL cause a crash like this: > > | 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. ... > ticerex said when I've asked him about his real name+email for the patches: > "Please use my forum nick." > <https://forum.openwrt.org/t/my-book-live-duo-reboot-loop/122464/14> > (I know checkpatch.pl complains about that. But what can you do?) I think Reported-by: is fine to have any kind of reference to the reporter. I can consider it false positive. ... > -#define SATA_DWC_QCMD_MAX 32 > +#define SATA_DWC_QCMD_MAX 33 Can't we use #define SATA_DWC_QCMD_MAX (ATA_TAG_INTERNAL + 1) instead? -- With Best Regards, Andy Shevchenko
