linux-kernel - [PATCH] btrfs: Refactor allocation size calculation in kzalloc()

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Message-ID: <20250930091440.25078-1-mehdi.benhadjkhelifa@gmail.com>
Date: Tue, 30 Sep 2025 10:14:22 +0100
From: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
To: clm@...com,
	dsterba@...e.com
Cc: linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	skhan@...uxfoundation.org,
	david.hunter.linux@...il.com,
	linux-kernel-mentees@...ts.linuxfoundation.org,
	Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
Subject: [PATCH] btrfs: Refactor allocation size calculation in kzalloc()

Wrap allocation size calculation in size_add() and size_mul() to avoid
any potential overflow.

Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
---
 fs/btrfs/volumes.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c6e3efd6f602..3f1f19b28aac 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6076,12 +6076,11 @@ struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_info,
 {
 	struct btrfs_io_context *bioc;
 
-	bioc = kzalloc(
-		 /* The size of btrfs_io_context */
-		sizeof(struct btrfs_io_context) +
-		/* Plus the variable array for the stripes */
-		sizeof(struct btrfs_io_stripe) * (total_stripes),
-		GFP_NOFS);
+	/* The size of btrfs_io_context */
+	/* Plus the variable array for the stripes */
+	bioc = kzalloc(size_add(sizeof(struct btrfs_io_context),
+				size_mul(sizeof(struct btrfs_io_stripe),
+						total_stripes)), GFP_NOFS);
 
 	if (!bioc)
 		return NULL;
-- 
2.51.0