+ aio-fix-mremap-after-fork-null-deref.patch added to mm-hotfixes-unstable branch

+ aio-fix-mremap-after-fork-null-deref.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: aio: fix mremap after fork null-deref
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     aio-fix-mremap-after-fork-null-deref.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/aio-fix-mremap-after-fork-null-deref.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Seth Jenkins <sethjenkins@google.com>
Subject: aio: fix mremap after fork null-deref
Date: Fri, 4 Nov 2022 17:25:19 -0400

Commit e4a0d3e720e7 ("aio: Make it possible to remap aio ring") introduced
a null-deref if mremap is called on an old aio mapping after fork as
mm->ioctx_table will be set to NULL.

Link: https://lkml.kernel.org/r/20221104212519.538108-1-sethjenkins@google.com
Fixes: e4a0d3e720e7 ("aio: Make it possible to remap aio ring")
Signed-off-by: Seth Jenkins <sethjenkins@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Jann Horn <jannh@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/aio.c |   18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

--- a/fs/aio.c~aio-fix-mremap-after-fork-null-deref
+++ a/fs/aio.c
@@ -361,16 +361,18 @@ static int aio_ring_mremap(struct vm_are
 	spin_lock(&mm->ioctx_lock);
 	rcu_read_lock();
 	table = rcu_dereference(mm->ioctx_table);
-	for (i = 0; i < table->nr; i++) {
-		struct kioctx *ctx;
+	if (table) {
+		for (i = 0; i < table->nr; i++) {
+			struct kioctx *ctx;
 
-		ctx = rcu_dereference(table->table[i]);
-		if (ctx && ctx->aio_ring_file == file) {
-			if (!atomic_read(&ctx->dead)) {
-				ctx->user_id = ctx->mmap_base = vma->vm_start;
-				res = 0;
+			ctx = rcu_dereference(table->table[i]);
+			if (ctx && ctx->aio_ring_file == file) {
+				if (!atomic_read(&ctx->dead)) {
+					ctx->user_id = ctx->mmap_base = vma->vm_start;
+					res = 0;
+				}
+				break;
 			}
-			break;
 		}
 	}
 
_

Patches currently in -mm which might be from sethjenkins@google.com are

aio-fix-mremap-after-fork-null-deref.patch

+ aio-fix-mremap-after-fork-null-deref.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: aio: fix mremap after fork null-deref
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     aio-fix-mremap-after-fork-null-deref.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/aio-fix-mremap-after-fork-null-deref.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Seth Jenkins <sethjenkins@google.com>
Subject: aio: fix mremap after fork null-deref
Date: Tue, 31 Jan 2023 12:25:55 -0500

Commit e4a0d3e720e7 ("aio: Make it possible to remap aio ring") introduced
a null-deref if mremap is called on an old aio mapping after fork as
mm->ioctx_table will be set to NULL.

[jmoyer@redhat.com: fix 80 column issue]
Link: https://lkml.kernel.org/r/x49sffq4nvg.fsf@segfault.boston.devel.redhat.com
Fixes: e4a0d3e720e7 ("aio: Make it possible to remap aio ring")
Signed-off-by: Seth Jenkins <sethjenkins@google.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Jann Horn <jannh@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/aio.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/aio.c~aio-fix-mremap-after-fork-null-deref
+++ a/fs/aio.c
@@ -361,6 +361,9 @@ static int aio_ring_mremap(struct vm_are
 	spin_lock(&mm->ioctx_lock);
 	rcu_read_lock();
 	table = rcu_dereference(mm->ioctx_table);
+	if (!table)
+		goto out_unlock;
+
 	for (i = 0; i < table->nr; i++) {
 		struct kioctx *ctx;
 
@@ -374,6 +377,7 @@ static int aio_ring_mremap(struct vm_are
 		}
 	}
 
+out_unlock:
 	rcu_read_unlock();
 	spin_unlock(&mm->ioctx_lock);
 	return res;
_

Patches currently in -mm which might be from sethjenkins@google.com are

aio-fix-mremap-after-fork-null-deref.patch