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Subject[ 17/48] staging:rts_pstor:Fix possible panic by NULL pointer dereference
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
From: wwang <wei_wang@realsil.com.cn>

commit 0d05568ac79bfc595f1eadc3e0fd7a20a45f7b69 upstream.

rtsx_transport.c (rtsx_transfer_sglist_adma_partial):
pointer struct scatterlist *sg, which is mapped in dma_map_sg,
is used as an iterator in later transfer operation. It is corrupted and
passed to dma_unmap_sg, thus causing fatal unmap of some erroneous address.
Fix it by duplicating *sg_ptr for iterating.

Signed-off-by: wwang <wei_wang@realsil.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/staging/rts_pstor/rtsx_transport.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/rts_pstor/rtsx_transport.c b/drivers/staging/rts_pstor/rtsx_transport.c
index 4e3d2c1..9b2e5c9 100644
--- a/drivers/staging/rts_pstor/rtsx_transport.c
+++ b/drivers/staging/rts_pstor/rtsx_transport.c
@@ -335,6 +335,7 @@ static int rtsx_transfer_sglist_adma_partial(struct rtsx_chip *chip, u8 card,
int sg_cnt, i, resid;
int err = 0;
long timeleft;
+ struct scatterlist *sg_ptr;
u32 val = TRIG_DMA;

if ((sg == NULL) || (num_sg <= 0) || !offset || !index)
@@ -371,7 +372,7 @@ static int rtsx_transfer_sglist_adma_partial(struct rtsx_chip *chip, u8 card,
sg_cnt = dma_map_sg(&(rtsx->pci->dev), sg, num_sg, dma_dir);

resid = size;
-
+ sg_ptr = sg;
chip->sgi = 0;
/* Usually the next entry will be @sg@ + 1, but if this sg element
* is part of a chained scatterlist, it could jump to the start of
@@ -379,14 +380,14 @@ static int rtsx_transfer_sglist_adma_partial(struct rtsx_chip *chip, u8 card,
* the proper sg
*/
for (i = 0; i < *index; i++)
- sg = sg_next(sg);
+ sg_ptr = sg_next(sg_ptr);
for (i = *index; i < sg_cnt; i++) {
dma_addr_t addr;
unsigned int len;
u8 option;

- addr = sg_dma_address(sg);
- len = sg_dma_len(sg);
+ addr = sg_dma_address(sg_ptr);
+ len = sg_dma_len(sg_ptr);

RTSX_DEBUGP("DMA addr: 0x%x, Len: 0x%x\n",
(unsigned int)addr, len);
@@ -415,7 +416,7 @@ static int rtsx_transfer_sglist_adma_partial(struct rtsx_chip *chip, u8 card,
if (!resid)
break;

- sg = sg_next(sg);
+ sg_ptr = sg_next(sg_ptr);
}

RTSX_DEBUGP("SG table count = %d\n", chip->sgi);



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