From e7737c89eb9ef5677a3b21141b6f8eb1e47c958e Mon Sep 17 00:00:00 2001 From: David Lamparter Date: Tue, 19 Sep 2023 21:03:24 +0200 Subject: [PATCH] lib: constrain hash table "tabshift" both ways The previous change to assume() did address the coverity warning about one direction of the shift in HASH_KEY, let's constrain the other in HASH_SIZE as well. To be fair, the hash table *will* break at 1G entries, but at that point we have other problems RAM-wise. (Could bump the thing to 64-bit, but then we need better item hash functions too on every single user.) Signed-off-by: David Lamparter --- lib/typesafe.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/lib/typesafe.h b/lib/typesafe.h index a84298b0629f..93258c595410 100644 --- a/lib/typesafe.h +++ b/lib/typesafe.h @@ -795,13 +795,16 @@ struct thash_head { uint8_t minshift, maxshift; }; -#define _HASH_SIZE(tabshift) \ - ((1U << (tabshift)) >> 1) +#define _HASH_SIZE(tabshift) \ + ({ \ + assume((tabshift) <= 31); \ + (1U << (tabshift)) >> 1; \ + }) #define HASH_SIZE(head) \ _HASH_SIZE((head).tabshift) #define _HASH_KEY(tabshift, val) \ ({ \ - assume((tabshift) >= 2 && (tabshift) <= 33); \ + assume((tabshift) >= 2 && (tabshift) <= 31); \ (val) >> (33 - (tabshift)); \ }) #define HASH_KEY(head, val) \