From 8351760ff5b2042039554b4948ddabaac644a976 Mon Sep 17 00:00:00 2001 From: Yury Norov Date: Thu, 5 Apr 2018 16:18:25 -0700 Subject: lib: fix stall in __bitmap_parselist() syzbot is catching stalls at __bitmap_parselist() (https://syzkaller.appspot.com/bug?id=ad7e0351fbc90535558514a71cd3edc11681997a). The trigger is unsigned long v = 0; bitmap_parselist("7:,", &v, BITS_PER_LONG); which results in hitting infinite loop at while (a <= b) { off = min(b - a + 1, used_size); bitmap_set(maskp, a, off); a += group_size; } due to used_size == group_size == 0. Link: http://lkml.kernel.org/r/20180404162647.15763-1-ynorov@caviumnetworks.com Fixes: 0a5ce0831d04382a ("lib/bitmap.c: make bitmap_parselist() thread-safe and much faster") Signed-off-by: Yury Norov Reported-by: Tetsuo Handa Reported-by: syzbot Cc: Noam Camus Cc: Rasmus Villemoes Cc: Matthew Wilcox Cc: Mauro Carvalho Chehab Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/bitmap.c | 2 +- lib/test_bitmap.c | 4 ++++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/lib/bitmap.c b/lib/bitmap.c index 9e498c77ed0e..a42eff7e8c48 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -607,7 +607,7 @@ static int __bitmap_parselist(const char *buf, unsigned int buflen, /* if no digit is after '-', it's wrong*/ if (at_start && in_range) return -EINVAL; - if (!(a <= b) || !(used_size <= group_size)) + if (!(a <= b) || group_size == 0 || !(used_size <= group_size)) return -EINVAL; if (b >= nmaskbits) return -ERANGE; diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c index b3f235baa05d..413367cf569e 100644 --- a/lib/test_bitmap.c +++ b/lib/test_bitmap.c @@ -255,6 +255,10 @@ static const struct test_bitmap_parselist parselist_tests[] __initconst = { {-EINVAL, "-1", NULL, 8, 0}, {-EINVAL, "-0", NULL, 8, 0}, {-EINVAL, "10-1", NULL, 8, 0}, + {-EINVAL, "0-31:", NULL, 8, 0}, + {-EINVAL, "0-31:0", NULL, 8, 0}, + {-EINVAL, "0-31:0/0", NULL, 8, 0}, + {-EINVAL, "0-31:1/0", NULL, 8, 0}, {-EINVAL, "0-31:10/1", NULL, 8, 0}, }; -- cgit v1.2.3