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authorChristian Lamparter <chunkeey@gmail.com>2022-03-19 21:11:02 +0100
committerDamien Le Moal <damien.lemoal@opensource.wdc.com>2022-04-04 09:56:34 +0900
commit7aa8104a554713b685db729e66511b93d989dd6a (patch)
tree069c785396c2d6c7dc34a7b974bf11d8c0530104 /drivers/ata
parent76ed2f61ae3ee5ca6e3ef155a703ab3eee1eb295 (diff)
downloadlinux-7aa8104a554713b685db729e66511b93d989dd6a.tar.bz2
ata: sata_dwc_460ex: Fix crash due to OOB write
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> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Diffstat (limited to 'drivers/ata')
-rw-r--r--drivers/ata/sata_dwc_460ex.c6
1 files changed, 5 insertions, 1 deletions
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;