FAILED: patch "[PATCH] pseries/papr-hvpipe: Fix race with interrupt handler" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] pseries/papr-hvpipe: Fix race with interrupt handler" failed to apply to 6.18-stable tree

[gregkh]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 7a4f0846ee6cc8cf44ae0046ed42e3259d1dd45b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026051217-briskness-posing-6f46@gregkh' --subject-prefix 'PATCH 6.18.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7a4f0846ee6cc8cf44ae0046ed42e3259d1dd45b Mon Sep 17 00:00:00 2001
From: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Date: Fri, 1 May 2026 09:41:40 +0530
Subject: [PATCH] pseries/papr-hvpipe: Fix race with interrupt handler

While executing ->ioctl handler or ->release handler, if an interrupt
fires on the same cpu, then we can enter into a deadlock.

This patch fixes both these handlers to take spin_lock_irq{save|restore}
versions of the lock to prevent this deadlock.

Cc: stable@vger.kernel.org
Fixes: 814ef095f12c9 ("powerpc/pseries: Add papr-hvpipe char driver for HVPIPE interfaces")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/e4ed435c44fc191f2eb23c7907ba6f72f193e6aa.1777606826.git.ritesh.list@gmail.com

diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index 14ae480d060a..c41d45e1986d 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -444,13 +444,14 @@ static int papr_hvpipe_handle_release(struct inode *inode,
 				struct file *file)
 {
 	struct hvpipe_source_info *src_info;
+	unsigned long flags;
 
 	/*
 	 * Hold the lock, remove source from src_list, reset the
 	 * hvpipe status and release the lock to prevent any race
 	 * with message event IRQ.
 	 */
-	spin_lock(&hvpipe_src_list_lock);
+	spin_lock_irqsave(&hvpipe_src_list_lock, flags);
 	src_info = file->private_data;
 	list_del(&src_info->list);
 	file->private_data = NULL;
@@ -461,10 +462,10 @@ static int papr_hvpipe_handle_release(struct inode *inode,
 	 */
 	if (src_info->hvpipe_status & HVPIPE_MSG_AVAILABLE) {
 		src_info->hvpipe_status = 0;
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 		hvpipe_rtas_recv_msg(NULL, 0);
 	} else
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 
 	kfree(src_info);
 	return 0;
@@ -480,20 +481,21 @@ static const struct file_operations papr_hvpipe_handle_ops = {
 static int papr_hvpipe_dev_create_handle(u32 srcID)
 {
 	struct hvpipe_source_info *src_info __free(kfree) = NULL;
+	unsigned long flags;
 
-	spin_lock(&hvpipe_src_list_lock);
+	spin_lock_irqsave(&hvpipe_src_list_lock, flags);
 	/*
 	 * Do not allow more than one process communicates with
 	 * each source.
 	 */
 	src_info = hvpipe_find_source(srcID);
 	if (src_info) {
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 		pr_err("pid(%d) is already using the source(%d)\n",
 				src_info->tsk->pid, srcID);
 		return -EALREADY;
 	}
-	spin_unlock(&hvpipe_src_list_lock);
+	spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 
 	src_info = kzalloc_obj(*src_info, GFP_KERNEL_ACCOUNT);
 	if (!src_info)
@@ -510,18 +512,18 @@ static int papr_hvpipe_dev_create_handle(u32 srcID)
 		return fdf.err;
 
 	retain_and_null_ptr(src_info);
-	spin_lock(&hvpipe_src_list_lock);
+	spin_lock_irqsave(&hvpipe_src_list_lock, flags);
 	/*
 	 * If two processes are executing ioctl() for the same
 	 * source ID concurrently, prevent the second process to
 	 * acquire FD.
 	 */
 	if (hvpipe_find_source(srcID)) {
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 		return -EALREADY;
 	}
 	list_add(&src_info->list, &hvpipe_src_list);
-	spin_unlock(&hvpipe_src_list_lock);
+	spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 	return fd_publish(fdf);
 }
 

[PATCH 6.18.y 1/2] papr-hvpipe: convert papr_hvpipe_dev_create_handle() to FD_PREPARE()

[Sasha Levin]

From: Christian Brauner <brauner@kernel.org>

[ Upstream commit 6d3789d347a7af5c4b0b2da3af47b8d9da607ab2 ]

Fixes a UAF for src_info as well.

Link: https://patch.msgid.link/20251123-work-fd-prepare-v4-33-b6efa1706cfd@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: 7a4f0846ee6c ("pseries/papr-hvpipe: Fix race with interrupt handler")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 39 +++++---------------
 1 file changed, 9 insertions(+), 30 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index 21a2f447c43fd..dd7b668799d9b 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -479,10 +479,7 @@ static const struct file_operations papr_hvpipe_handle_ops = {
 
 static int papr_hvpipe_dev_create_handle(u32 srcID)
 {
-	struct hvpipe_source_info *src_info;
-	struct file *file;
-	long err;
-	int fd;
+	struct hvpipe_source_info *src_info __free(kfree) = NULL;
 
 	spin_lock(&hvpipe_src_list_lock);
 	/*
@@ -506,20 +503,13 @@ static int papr_hvpipe_dev_create_handle(u32 srcID)
 	src_info->tsk = current;
 	init_waitqueue_head(&src_info->recv_wqh);
 
-	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
-	if (fd < 0) {
-		err = fd;
-		goto free_buf;
-	}
-
-	file = anon_inode_getfile("[papr-hvpipe]",
-			&papr_hvpipe_handle_ops, (void *)src_info,
-			O_RDWR);
-	if (IS_ERR(file)) {
-		err = PTR_ERR(file);
-		goto free_fd;
-	}
+	FD_PREPARE(fdf, O_RDONLY | O_CLOEXEC,
+		   anon_inode_getfile("[papr-hvpipe]", &papr_hvpipe_handle_ops,
+				      (void *)src_info, O_RDWR));
+	if (fdf.err)
+		return fdf.err;
 
+	retain_and_null_ptr(src_info);
 	spin_lock(&hvpipe_src_list_lock);
 	/*
 	 * If two processes are executing ioctl() for the same
@@ -528,22 +518,11 @@ static int papr_hvpipe_dev_create_handle(u32 srcID)
 	 */
 	if (hvpipe_find_source(srcID)) {
 		spin_unlock(&hvpipe_src_list_lock);
-		err = -EALREADY;
-		goto free_file;
+		return -EALREADY;
 	}
 	list_add(&src_info->list, &hvpipe_src_list);
 	spin_unlock(&hvpipe_src_list_lock);
-
-	fd_install(fd, file);
-	return fd;
-
-free_file:
-	fput(file);
-free_fd:
-	put_unused_fd(fd);
-free_buf:
-	kfree(src_info);
-	return err;
+	return fd_publish(fdf);
 }
 
 /*
-- 
2.53.0

[PATCH 6.18.y 2/2] pseries/papr-hvpipe: Fix race with interrupt handler

[Sasha Levin]

From: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>

[ Upstream commit 7a4f0846ee6cc8cf44ae0046ed42e3259d1dd45b ]

While executing ->ioctl handler or ->release handler, if an interrupt
fires on the same cpu, then we can enter into a deadlock.

This patch fixes both these handlers to take spin_lock_irq{save|restore}
versions of the lock to prevent this deadlock.

Cc: stable@vger.kernel.org
Fixes: 814ef095f12c9 ("powerpc/pseries: Add papr-hvpipe char driver for HVPIPE interfaces")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/e4ed435c44fc191f2eb23c7907ba6f72f193e6aa.1777606826.git.ritesh.list@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index dd7b668799d9b..3df22407efae0 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -444,13 +444,14 @@ static int papr_hvpipe_handle_release(struct inode *inode,
 				struct file *file)
 {
 	struct hvpipe_source_info *src_info;
+	unsigned long flags;
 
 	/*
 	 * Hold the lock, remove source from src_list, reset the
 	 * hvpipe status and release the lock to prevent any race
 	 * with message event IRQ.
 	 */
-	spin_lock(&hvpipe_src_list_lock);
+	spin_lock_irqsave(&hvpipe_src_list_lock, flags);
 	src_info = file->private_data;
 	list_del(&src_info->list);
 	file->private_data = NULL;
@@ -461,10 +462,10 @@ static int papr_hvpipe_handle_release(struct inode *inode,
 	 */
 	if (src_info->hvpipe_status & HVPIPE_MSG_AVAILABLE) {
 		src_info->hvpipe_status = 0;
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 		hvpipe_rtas_recv_msg(NULL, 0);
 	} else
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 
 	kfree(src_info);
 	return 0;
@@ -480,20 +481,21 @@ static const struct file_operations papr_hvpipe_handle_ops = {
 static int papr_hvpipe_dev_create_handle(u32 srcID)
 {
 	struct hvpipe_source_info *src_info __free(kfree) = NULL;
+	unsigned long flags;
 
-	spin_lock(&hvpipe_src_list_lock);
+	spin_lock_irqsave(&hvpipe_src_list_lock, flags);
 	/*
 	 * Do not allow more than one process communicates with
 	 * each source.
 	 */
 	src_info = hvpipe_find_source(srcID);
 	if (src_info) {
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 		pr_err("pid(%d) is already using the source(%d)\n",
 				src_info->tsk->pid, srcID);
 		return -EALREADY;
 	}
-	spin_unlock(&hvpipe_src_list_lock);
+	spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 
 	src_info = kzalloc(sizeof(*src_info), GFP_KERNEL_ACCOUNT);
 	if (!src_info)
@@ -510,18 +512,18 @@ static int papr_hvpipe_dev_create_handle(u32 srcID)
 		return fdf.err;
 
 	retain_and_null_ptr(src_info);
-	spin_lock(&hvpipe_src_list_lock);
+	spin_lock_irqsave(&hvpipe_src_list_lock, flags);
 	/*
 	 * If two processes are executing ioctl() for the same
 	 * source ID concurrently, prevent the second process to
 	 * acquire FD.
 	 */
 	if (hvpipe_find_source(srcID)) {
-		spin_unlock(&hvpipe_src_list_lock);
+		spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 		return -EALREADY;
 	}
 	list_add(&src_info->list, &hvpipe_src_list);
-	spin_unlock(&hvpipe_src_list_lock);
+	spin_unlock_irqrestore(&hvpipe_src_list_lock, flags);
 	return fd_publish(fdf);
 }
 
-- 
2.53.0