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Subject[PATCH] afs: use BIT_ULL for shifting to fix integer overflow
Date
From: Colin Ian King <colin.king@canonical.com>

The expression 1 << nr_slots is evaluated with 32 bit integer arithmetic
and can overflow before it is widened. Instead, use BIT_ULL to avoid
overflow.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 63a4681ff39c ("afs: Locally edit directory data for mkdir/create/unlink/...")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
fs/afs/dir_edit.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/afs/dir_edit.c b/fs/afs/dir_edit.c
index d4fbe5f85f1b..f360119923aa 100644
--- a/fs/afs/dir_edit.c
+++ b/fs/afs/dir_edit.c
@@ -36,7 +36,7 @@ static int afs_find_contig_bits(union afs_xdr_dir_block *block, unsigned int nr_
bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8;
bitmap >>= 1; /* The first entry is metadata */
bit = 1;
- mask = (1 << nr_slots) - 1;
+ mask = BIT_ULL(nr_slots) - 1;

do {
if (sizeof(unsigned long) == 8)
@@ -70,7 +70,7 @@ static void afs_set_contig_bits(union afs_xdr_dir_block *block,
{
u64 mask, before, after;

- mask = (1 << nr_slots) - 1;
+ mask = BIT_ULL(nr_slots) - 1;
mask <<= bit;

before = *(u64 *)block->hdr.bitmap;
@@ -95,7 +95,7 @@ static void afs_clear_contig_bits(union afs_xdr_dir_block *block,
{
u64 mask, before, after;

- mask = (1 << nr_slots) - 1;
+ mask = BIT_ULL(nr_slots) - 1;
mask <<= bit;

before = *(u64 *)block->hdr.bitmap;
--
2.20.1
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