linux-kernel - [PATCH 56/56] xfs/libxfs: replace kmalloc() and memcpy() with kmemdup()

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Message-ID: <173888087646.2739176.5488711241017629414.stgit@frogsfrogsfrogs>
Date: Thu, 06 Feb 2025 14:49:44 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: djwong@...nel.org, aalbersh@...nel.org
Cc: cem@...nel.org, chandanbabu@...nel.org, dchinner@...hat.com,
 linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
 mtodorovac69@...il.com, cem@...nel.org, hch@....de, linux-xfs@...r.kernel.org
Subject: [PATCH 56/56] xfs/libxfs: replace kmalloc() and memcpy() with
 kmemdup()

From: Mirsad Todorovac <mtodorovac69@...il.com>

Source kernel commit: 9d9b72472631262b35157f1a650f066c0e11c2bb

The source static analysis tool gave the following advice:

./fs/xfs/libxfs/xfs_dir2.c:382:15-22: WARNING opportunity for kmemdup

→ 382         args->value = kmalloc(len,
383                          GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_RETRY_MAYFAIL);
384         if (!args->value)
385                 return -ENOMEM;
386
→ 387         memcpy(args->value, name, len);
388         args->valuelen = len;
389         return -EEXIST;

Replacing kmalloc() + memcpy() with kmemdump() doesn't change semantics.
Original code works without fault, so this is not a bug fix but proposed improvement.

Link: https://lwn.net/Articles/198928/
Fixes: 94a69db2367ef ("xfs: use __GFP_NOLOCKDEP instead of GFP_NOFS")
Fixes: 384f3ced07efd ("[XFS] Return case-insensitive match for dentry cache")
Fixes: 2451337dd0439 ("xfs: global error sign conversion")
Cc: Carlos Maiolino <cem@...nel.org>
Cc: Darrick J. Wong <djwong@...nel.org>
Cc: Chandan Babu R <chandanbabu@...nel.org>
Cc: Dave Chinner <dchinner@...hat.com>
Cc: linux-xfs@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Reviewed-by: "Darrick J. Wong" <djwong@...nel.org>
Signed-off-by: Mirsad Todorovac <mtodorovac69@...il.com>
Signed-off-by: Carlos Maiolino <cem@...nel.org>
---
 include/kmem.h    |    9 +++++++++
 libxfs/xfs_dir2.c |    3 +--
 2 files changed, 10 insertions(+), 2 deletions(-)


diff --git a/include/kmem.h b/include/kmem.h
index 16a7957f1acee3..66f8b1fbea8fdf 100644
--- a/include/kmem.h
+++ b/include/kmem.h
@@ -79,4 +79,13 @@ static inline void kfree_rcu_mightsleep(const void *ptr)
 __attribute__((format(printf,2,3)))
 char *kasprintf(gfp_t gfp, const char *fmt, ...);
 
+static inline void *kmemdup(const void *src, size_t len, gfp_t gfp)
+{
+	void *p = kmalloc(len, gfp);
+
+	if (p)
+		memcpy(p, src, len);
+	return p;
+}
+
 #endif
diff --git a/libxfs/xfs_dir2.c b/libxfs/xfs_dir2.c
index 29e64603d4ae82..1285019b674423 100644
--- a/libxfs/xfs_dir2.c
+++ b/libxfs/xfs_dir2.c
@@ -378,12 +378,11 @@ xfs_dir_cilookup_result(
 					!(args->op_flags & XFS_DA_OP_CILOOKUP))
 		return -EEXIST;
 
-	args->value = kmalloc(len,
+	args->value = kmemdup(name, len,
 			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_RETRY_MAYFAIL);
 	if (!args->value)
 		return -ENOMEM;
 
-	memcpy(args->value, name, len);
 	args->valuelen = len;
 	return -EEXIST;
 }