Re: Regression - 2.6.24-rc3 - umem nvram card driver oops

From: Neil Brown
Date: Mon Dec 03 2007 - 19:14:28 EST


On Tuesday December 4, dgc@xxxxxxx wrote:
> Neil,
>
> I just upgraded an ia64 (Altix, 16k page size) test box to 2.6.24-rc3
> from 2.6.23 and I get it panicing on boot in the umem driver.

Cool - someone is using umem! And even testing it. Thanks!

A quick look shows a probable NULL deref. Let me know if this fixes
it. I'll read through the offending patch more carefully and make
sure there is nothing else wrong.

NeilBrown


Fix possible NULL dereference in umem.c

Signed-off-by: Neil Brown <neilb@xxxxxxx>

### Diffstat output
./drivers/block/umem.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff .prev/drivers/block/umem.c ./drivers/block/umem.c
--- .prev/drivers/block/umem.c 2007-12-04 11:11:30.000000000 +1100
+++ ./drivers/block/umem.c 2007-12-04 11:11:42.000000000 +1100
@@ -484,7 +484,8 @@ static void process_page(unsigned long d
page->idx++;
if (page->idx >= bio->bi_vcnt) {
page->bio = bio->bi_next;
- page->idx = page->bio->bi_idx;
+ if (page->bio)
+ page->idx = page->bio->bi_idx;
}

pci_unmap_page(card->dev, desc->data_dma_handle,


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