Messages in this thread | | | Subject | Re: [PATCH] mm: cma: Fix potential null dereference on pointer cma | From | John Hubbard <> | Date | Wed, 17 Mar 2021 00:13:31 -0700 |
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On 3/16/21 3:04 AM, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > At the start of the function there is a null pointer check on cma > and then branch to error handling label 'out'. The subsequent call > to cma_sysfs_fail_pages_count dereferences cma, hence there is a > potential null pointer deference issue. Fix this by only calling
As far as I can tell, it's not possible to actually cause that null failure with the existing kernel code paths. *Might* be worth mentioning that here (unless I'm wrong), but either way, looks good, so:
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
thanks, -- John Hubbard NVIDIA
> cma_sysfs_fail_pages_count if cma is not null. > > Addresses-Coverity: ("Dereference after null check") > Fixes: dc4764f7e9ac ("mm: cma: support sysfs") > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > mm/cma.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/cma.c b/mm/cma.c > index 6d4dbafdb318..90e27458ddb7 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -512,7 +512,8 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, > cma_sysfs_alloc_pages_count(cma, count); > } else { > count_vm_event(CMA_ALLOC_FAIL); > - cma_sysfs_fail_pages_count(cma, count); > + if (cma) > + cma_sysfs_fail_pages_count(cma, count); > } > > return page; >
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