Function mxcmci_request() throw an exception on a imx27 cpu.
This patch fix the problem by test the pointer before access it.
[ 516.783407] Unable to handle kernel NULL pointer dereference at virtual address 00000004
[ 516.791639] pgd = c0004000
[ 516.794445] [00000004] *pgd=00000000
[ 516.798088] Internal error: Oops: 17 [#1] ARM
[ 516.802472] Modules linked in:
[ 516.805593] CPU: 0 PID: 569 Comm: mmcqd/0 Not tainted 3.13.0-rc1-next-20131125-00006-g5f6bb77-dirty #66
[ 516.815027] task: cfb8a2a0 ti: cfb88000 task.ti: cfb88000
[ 516.820484] PC is at mxcmci_request+0xd0/0x2f8
[ 516.824974] LR is at mxcmci_request+0xf8/0x2f8
[ 516.829466] pc : [<c02b6048>] lr : [<c02b6070>] psr: 00000013
[ 516.829466] sp : cfb89dd0 ip : cfb89dd0 fp : cfb89e1c
[ 516.840988] r10: 000001ff r9 : 00000002 r8 : cfa10620
[ 516.846250] r7 : 00000200 r6 : cfa0f02c r5 : cfa0f0ec r4 : cfa10400
[ 516.852812] r3 : a0000013 r2 : cfa0f410 r1 : 00040000 r0 : 00000000
[ 516.859376] Flags: nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel
[ 516.866723] Control: 0005317f Table: afa74000 DAC: 00000017
[ 516.872503] Process mmcqd/0 (pid: 569, stack limit = 0xcfb881c0)
[ 516.878543] Stack: (0xcfb89dd0 to 0xcfb8a000)
(gdb) list *(mxcmci_request+0xd0)
0xcac is at drivers/mmc/host/mxcmmc.c:350.
345
346 if (!mxcmci_use_dma(host))
347 return 0;
348
349 for_each_sg(data->sg, sg, data->sg_len, i) {
350 if (sg->offset & 3 || sg->length & 3 || sg->length < 512) {
351 host->do_dma = 0;
352 return 0;
353 }
354 }
Signed-off-by: Chris Ruehl <chris.ruehl@xxxxxxxxxxxx>
---
drivers/mmc/host/mxcmmc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/mmc/host/mxcmmc.c b/drivers/mmc/host/mxcmmc.c
index f7199c8..8645d6a 100644
--- a/drivers/mmc/host/mxcmmc.c
+++ b/drivers/mmc/host/mxcmmc.c
@@ -347,7 +347,7 @@ static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data)
return 0;
for_each_sg(data->sg, sg, data->sg_len, i) {
- if (sg->offset & 3 || sg->length & 3 || sg->length < 512) {
+ if (sg && (sg->offset & 3 || sg->length & 3 || sg->length < 512)) {
host->do_dma = 0;
return 0;
}
--
1.7.10.4
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