Messages in this thread | | | Date | Tue, 7 Nov 2023 23:29:53 +0800 | From | Chao Yu <> | Subject | Re: [PATCH] f2fs: data: fix possible overflow in check_swap_activate() |
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Hi Sergey,
Thanks for the patch.
On 2023/10/26 4:20, Sergey Shtylyov wrote: > In check_swap_activate(), if the *while* loop exits early (0- or 1-page > long swap file), an overflow happens while calculating the value of the > span parameter as the lowest_pblock variable ends up being greater than > the highest_pblock variable. Let's set *span to 0 in this case...
What do you think of returning -EINVAL for such case? I assume this is a corner case.
> > Found by Linux Verification Center (linuxtesting.org) with the SVACE static > analysis tool. > > Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru> > --- > This patch is against the 'master' branch of Jaegeuk Kim's F2FS repo... > > fs/f2fs/data.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index 916e317ac925..342cb0d5056d 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -4047,7 +4047,10 @@ static int check_swap_activate(struct swap_info_struct *sis, > cur_lblock += nr_pblocks; > } > ret = nr_extents; > - *span = 1 + highest_pblock - lowest_pblock; > + if (lowest_pblock <= highest_pblock)
if (unlikely(higest_pblock < lowest_pblock)) return -EINVAL;
*span = 1 + highest_pblock - lowest_pblock;
Thanks,
> + *span = 1 + highest_pblock - lowest_pblock; > + else > + *span = 0; > if (cur_lblock == 0) > cur_lblock = 1; /* force Empty message */ > sis->max = cur_lblock;
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