Messages in this thread Patch in this message |  | | From | Stepan Ionichev <> | | Subject | [PATCH] mmc: davinci: avoid NULL deref of host->data in IRQ handler | | Date | Thu, 7 May 2026 00:05:37 +0500 |
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mmc_davinci_irq() returns early only when both host->cmd and host->data are NULL:
if (host->cmd == NULL && host->data == NULL) { ... return IRQ_NONE; }
So we may legitimately reach the rest of the handler with host->data == NULL (and therefore data == NULL). The DATDNE branch already guards against this with an explicit "if (data != NULL)" check, but the subsequent TOUTRD ("read data timeout") and CRCWR/CRCRD ("data CRC error") branches dereference data unconditionally:
if (qstatus & MMCST0_TOUTRD) { data->error = -ETIMEDOUT; <-- NULL deref ... davinci_abort_data(host, data); }
if (qstatus & (MMCST0_CRCWR | MMCST0_CRCRD)) { data->error = -EILSEQ; <-- NULL deref ... }
If either bit is set in qstatus while host->data is NULL, the kernel will crash inside the IRQ handler. smatch flags this:
drivers/mmc/host/davinci_mmc.c:933 mmc_davinci_irq() error: we previously assumed 'data' could be null (see line 914)
Gate both branches on a non-NULL data, matching the existing pattern used by the DATDNE branch.
No functional change for callers where data is non-NULL, which is the only case in which these branches did meaningful work before this change.
Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com> --- drivers/mmc/host/davinci_mmc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c index 42b0118a4..42ad87aa4 100644 --- a/drivers/mmc/host/davinci_mmc.c +++ b/drivers/mmc/host/davinci_mmc.c @@ -928,7 +928,7 @@ static irqreturn_t mmc_davinci_irq(int irq, void *dev_id) } } - if (qstatus & MMCST0_TOUTRD) { + if (data && (qstatus & MMCST0_TOUTRD)) { /* Read data timeout */ data->error = -ETIMEDOUT; end_transfer = 1; @@ -940,7 +940,7 @@ static irqreturn_t mmc_davinci_irq(int irq, void *dev_id) davinci_abort_data(host, data); } - if (qstatus & (MMCST0_CRCWR | MMCST0_CRCRD)) { + if (data && (qstatus & (MMCST0_CRCWR | MMCST0_CRCRD))) { /* Data CRC error */ data->error = -EILSEQ; end_transfer = 1; -- 2.43.0
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