linux-kernel - [PATCH v1 1/1] test_firmware: return ENOMEM instead of ENOSPC on failed memory allocation

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Message-Id: <20230801185324.197544-1-mirsad.todorovac@alu.unizg.hr>
Date:   Tue,  1 Aug 2023 20:53:25 +0200
From:   Mirsad Todorovac <mirsad.todorovac@....unizg.hr>
To:     Mirsad Todorovac <mirsad.todorovac@....unizg.hr>,
        linux-kernel@...r.kernel.org
Cc:     Dan Carpenter <error27@...il.com>, Takashi Iwai <tiwai@...e.de>,
        Kees Cook <keescook@...omium.org>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        Brian Norris <computersforpeace@...il.com>,
        stable@...r.kernel.org
Subject: [PATCH v1 1/1] test_firmware: return ENOMEM instead of ENOSPC on failed memory allocation

[ Upstream commit 7dae593cd226a0bca61201cf85ceb9335cf63682 ]

In a couple of situations like

	name = kstrndup(buf, count, GFP_KERNEL);
	if (!name)
		return -ENOSPC;

the error is not actually "No space left on device", but "Out of memory".

It is semantically correct to return -ENOMEM in all failed kstrndup()
and kzalloc() cases in this driver, as it is not a problem with disk
space, but with kernel memory allocator failing allocation.

The semantically correct should be:

        name = kstrndup(buf, count, GFP_KERNEL);
        if (!name)
                return -ENOMEM;

Cc: Dan Carpenter <error27@...il.com>
Cc: Takashi Iwai <tiwai@...e.de>
Cc: Kees Cook <keescook@...omium.org>
Cc: Luis R. Rodriguez <mcgrof@...nel.org>
Cc: Brian Norris <computersforpeace@...il.com>
Cc: stable@...r.kernel.org # 4.19, 4.14
Fixes: c92316bf8e948 ("test_firmware: add batched firmware tests")
Fixes: 0a8adf584759c ("test: add firmware_class loader test")
Fixes: eb910947c82f9 ("test: firmware_class: add asynchronous request trigger")
Fixes: 061132d2b9c95 ("test_firmware: add test custom fallback trigger")
Link: https://lore.kernel.org/all/20230606070808.9300-1-mirsad.todorovac@alu.unizg.hr/
Signed-off-by: Mirsad Todorovac <mirsad.todorovac@....unizg.hr>

[ This is the backport of the patch to 4.19 and 4.14 branches. There are no	]
[ semantic differences in the commit. Backport is provided for completenes sake	]
[ so it would apply to all of the supported LTS kernels				]
---
v1:
 no semantic difference, but there is change in code (one less patched instance of -ENOSPC),
 so I am submitting the patch for a review.

 lib/test_firmware.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index e4688821eab8..b5e779bcfb34 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -160,7 +160,7 @@ static int __kstrncpy(char **dst, const char *name, size_t count, gfp_t gfp)
 {
 	*dst = kstrndup(name, count, gfp);
 	if (!*dst)
-		return -ENOSPC;
+		return -ENOMEM;
 	return count;
 }
 
@@ -456,7 +456,7 @@ static ssize_t trigger_request_store(struct device *dev,
 
 	name = kstrndup(buf, count, GFP_KERNEL);
 	if (!name)
-		return -ENOSPC;
+		return -ENOMEM;
 
 	pr_info("loading '%s'\n", name);
 
@@ -497,7 +497,7 @@ static ssize_t trigger_async_request_store(struct device *dev,
 
 	name = kstrndup(buf, count, GFP_KERNEL);
 	if (!name)
-		return -ENOSPC;
+		return -ENOMEM;
 
 	pr_info("loading '%s'\n", name);
 
@@ -540,7 +540,7 @@ static ssize_t trigger_custom_fallback_store(struct device *dev,
 
 	name = kstrndup(buf, count, GFP_KERNEL);
 	if (!name)
-		return -ENOSPC;
+		return -ENOMEM;
 
 	pr_info("loading '%s' using custom fallback mechanism\n", name);
 
-- 
2.34.1