Messages in this thread Patch in this message | | | Subject | Re: [PATCH] misc: genwqe: check for error from get_user_pages_fast() | From | Frank Haverkamp <> | Date | Tue, 02 Dec 2014 13:59:20 +0100 |
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Hi Ian,
thanks for reviewing our code and sorry for not answering immediately.
Am Donnerstag, den 06.11.2014, 16:23 +0000 schrieb Ian Abbott: > `genwqe_user_vmap()` calls `get_user_pages_fast()` and if the return > value is less than the number of pages requested, it frees the pages and > returns an error (`-EFAULT`). However, it fails to consider a negative > error return value from `get_user_pages_fast()`. In that case, the test > `if (rc < m->nr_pages)` will be false (due to promotion of `rc` to a > large `unsigned int`) and the code will continue on to call > `genwqe_map_pages()` with an invalid list of page pointers. Fix it by > bailing out if `get_user_pages_fast()` returns a negative error value.
True. Did you find this by manual inspection of the code or did you use tools to figure it out?
> > Signed-off-by: Ian Abbott <abbotti@mev.co.uk> > Cc: <stable@vger.kernel.org> # 3.14.x # 3.15.x # 3.16.x # 3.17.x > --- > drivers/misc/genwqe/card_utils.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c > index 7cb3b7e..1ca94e6 100644 > --- a/drivers/misc/genwqe/card_utils.c > +++ b/drivers/misc/genwqe/card_utils.c > @@ -590,6 +590,8 @@ int genwqe_user_vmap(struct genwqe_dev *cd, struct dma_mapping *m, void *uaddr, > m->nr_pages, > 1, /* write by caller */ > m->page_list); /* ptrs to pages */ > + if (rc < 0) > + goto fail_get_user_pages; > > /* assumption: get_user_pages can be killed by signals. */ > if (rc < m->nr_pages) {
Regards
Frank
Acked-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
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