linux-kernel - [PATCH] devres: zero the memory in devm

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Message-Id: <20201026122728.8522-1-brgl@bgdev.pl>
Date:   Mon, 26 Oct 2020 13:27:28 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH] devres: zero the memory in devm_krealloc() if needed

From: Bartosz Golaszewski <bgolaszewski@...libre.com>

If we're returning the same pointer (when new size is smaller or equal
to the old size) we need to check if the user wants the memory zeroed
and memset() it manually if so.

Fixes: f82485722e5d devres: provide devm_krealloc()
Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
---
 drivers/base/devres.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 586e9a75c840..e522ad5f8342 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -895,8 +895,12 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
 	 * If new size is smaller or equal to the actual number of bytes
 	 * allocated previously - just return the same pointer.
 	 */
-	if (total_new_size <= total_old_size)
+	if (total_new_size <= total_old_size) {
+		if (gfp & __GFP_ZERO)
+			memset(ptr, 0, new_size);
+
 		return ptr;
+	}
 
 	/*
 	 * Otherwise: allocate new, larger chunk. We need to allocate before
-- 
2.29.1