This is a note to let you know that I've just added the patch titled
efi: capsule-loader: Fix use-after-free in efi_capsule_write
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
efi-capsule-loader-fix-use-after-free-in-efi_capsule_write.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9cb636b5f6a8cc6d1b50809ec8f8d33ae0c84c95 Mon Sep 17 00:00:00 2001
From: Hyunwoo Kim <imv4bel@xxxxxxxxx>
Date: Wed, 7 Sep 2022 09:07:14 -0700
Subject: efi: capsule-loader: Fix use-after-free in efi_capsule_write
From: Hyunwoo Kim <imv4bel@xxxxxxxxx>
commit 9cb636b5f6a8cc6d1b50809ec8f8d33ae0c84c95 upstream.
A race condition may occur if the user calls close() on another thread
during a write() operation on the device node of the efi capsule.
This is a race condition that occurs between the efi_capsule_write() and
efi_capsule_flush() functions of efi_capsule_fops, which ultimately
results in UAF.
So, the page freeing process is modified to be done in
efi_capsule_release() instead of efi_capsule_flush().
Cc: <stable@xxxxxxxxxxxxxxx> # v4.9+
Signed-off-by: Hyunwoo Kim <imv4bel@xxxxxxxxx>
Link: https://lore.kernel.org/all/20220907102920.GA88602@ubuntu/
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/firmware/efi/capsule-loader.c | 31 +++++++------------------------
1 file changed, 7 insertions(+), 24 deletions(-)
--- a/drivers/firmware/efi/capsule-loader.c
+++ b/drivers/firmware/efi/capsule-loader.c
@@ -243,29 +243,6 @@ failed:
}
/**
- * efi_capsule_flush - called by file close or file flush
- * @file: file pointer
- * @id: not used
- *
- * If a capsule is being partially uploaded then calling this function
- * will be treated as upload termination and will free those completed
- * buffer pages and -ECANCELED will be returned.
- **/
-static int efi_capsule_flush(struct file *file, fl_owner_t id)
-{
- int ret = 0;
- struct capsule_info *cap_info = file->private_data;
-
- if (cap_info->index > 0) {
- pr_err("capsule upload not complete\n");
- efi_free_all_buff_pages(cap_info);
- ret = -ECANCELED;
- }
-
- return ret;
-}
-
-/**
* efi_capsule_release - called by file close
* @inode: not used
* @file: file pointer
@@ -277,6 +254,13 @@ static int efi_capsule_release(struct in
{
struct capsule_info *cap_info = file->private_data;
+ if (cap_info->index > 0 &&
+ (cap_info->header.headersize == 0 ||
+ cap_info->count < cap_info->total_size)) {
+ pr_err("capsule upload not complete\n");
+ efi_free_all_buff_pages(cap_info);
+ }
+
kfree(cap_info->pages);
kfree(cap_info->phys);
kfree(file->private_data);
@@ -324,7 +308,6 @@ static const struct file_operations efi_
.owner = THIS_MODULE,
.open = efi_capsule_open,
.write = efi_capsule_write,
- .flush = efi_capsule_flush,
.release = efi_capsule_release,
.llseek = no_llseek,
};
Patches currently in stable-queue which might be from imv4bel@xxxxxxxxx are
queue-5.15/efi-capsule-loader-fix-use-after-free-in-efi_capsule_write.patch
