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...
Found by Linux Verification Center (linuxtesting.org) with the SVACE static analysis tool. Signed-off-by: Sergey Shtylyov <s.shtyl...@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) + *span = 1 + highest_pblock - lowest_pblock; + else + *span = 0; if (cur_lblock == 0) cur_lblock = 1; /* force Empty message */ sis->max = cur_lblock; -- 2.26.3 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel