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FAILED: patch "[PATCH] ksmbd: fix race condition with fp" failed to apply to 6.5-stable tree

PATCH [email protected] 1 participant 1 message Oct 8, 2023

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Stable branch Kernel SMB3 server (ksmbd)
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The patch below does not apply to the 6.5-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 <[email protected]>.

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-6.5.y
git checkout FETCH_HEAD
git cherry-pick -x 5a7ee91d1154f35418367a6eaae74046fd06ed89
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023100854-usable-entree-9b37@gregkh' --subject-prefix 'PATCH 6.5.y' HEAD^..

Possible dependencies:

5a7ee91d1154 ("ksmbd: fix race condition with fp") e2b76ab8b5c9 ("ksmbd: add support for read compound")

thanks,

greg k-h

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

From 5a7ee91d1154f35418367a6eaae74046fd06ed89 Mon Sep 17 00:00:00 2001
From: Namjae Jeon <[email protected]>
Date: Wed, 4 Oct 2023 18:28:39 +0900
Subject: [PATCH] ksmbd: fix race condition with fp

fp can used in each command. If smb2_close command is coming at the same time, UAF issue can happen by race condition.

                           Time
                            +
Thread A                    | Thread B1 B2 .... B5
smb2_open                   | smb2_close
                            |
 __open_id                  |
   insert fp to file_table  |
                            |
                            |   atomic_dec_and_test(&fp->refcount)
                            |   if fp->refcount == 0, free fp by kfree.
 // UAF!                    |
 use fp                     |
                            +

This patch add f_state not to use freed fp is used and not to free fp in use.

Reported-by luosili <[email protected]>
Signed-off-by Namjae Jeon <[email protected]>
Signed-off-by Steve French <[email protected]>
fs/smb/server/smb2pdu.c +3 -1
index 544022dd6d20..420e7691c8cf 100644
@@ -3370,8 +3370,10 @@ int smb2_open(struct ksmbd_work *work)
 	}
 	ksmbd_revert_fsids(work);
 err_out1:
-	if (!rc)
+	if (!rc) {
+		ksmbd_update_fstate(&work->sess->file_table, fp, FP_INITED);
 		rc = ksmbd_iov_pin_rsp(work, (void *)rsp, iov_len);
+	}
 	if (rc) {
 		if (rc == -EINVAL)
 			rsp->hdr.Status = STATUS_INVALID_PARAMETER;
fs/smb/server/vfs_cache.c +20 -3
index f41f8d6108ce..c4b80ab7df74 100644
@@ -333,6 +333,9 @@ static void __ksmbd_close_fd(struct ksmbd_file_table *ft, struct ksmbd_file *fp)
 
 static struct ksmbd_file *ksmbd_fp_get(struct ksmbd_file *fp)
 {
+	if (fp->f_state != FP_INITED)
+		return NULL;
+
 	if (!atomic_inc_not_zero(&fp->refcount))
 		return NULL;
 	return fp;

@@ -382,15 +385,20 @@ int ksmbd_close_fd(struct ksmbd_work *work, u64 id)
 		return 0;
 
 	ft = &work->sess->file_table;
-	read_lock(&ft->lock);
+	write_lock(&ft->lock);
 	fp = idr_find(ft->idr, id);
 	if (fp) {
 		set_close_state_blocked_works(fp);
 
-		if (!atomic_dec_and_test(&fp->refcount))
+		if (fp->f_state != FP_INITED)
 			fp = NULL;
+		else {
+			fp->f_state = FP_CLOSED;
+			if (!atomic_dec_and_test(&fp->refcount))
+				fp = NULL;
+		}
 	}
-	read_unlock(&ft->lock);
+	write_unlock(&ft->lock);
 
 	if (!fp)
 		return -EINVAL;

@@ -570,6 +578,7 @@ struct ksmbd_file *ksmbd_open_fd(struct ksmbd_work *work, struct file *filp)
 	fp->tcon		= work->tcon;
 	fp->volatile_id		= KSMBD_NO_FID;
 	fp->persistent_id	= KSMBD_NO_FID;
+	fp->f_state		= FP_NEW;
 	fp->f_ci		= ksmbd_inode_get(fp);
 
 	if (!fp->f_ci) {

@@ -591,6 +600,14 @@ struct ksmbd_file *ksmbd_open_fd(struct ksmbd_work *work, struct file *filp)
 	return ERR_PTR(ret);
 }
 
+void ksmbd_update_fstate(struct ksmbd_file_table *ft, struct ksmbd_file *fp,
+			 unsigned int state)
+{
+	write_lock(&ft->lock);
+	fp->f_state = state;
+	write_unlock(&ft->lock);
+}
+
 static int
 __close_file_table_ids(struct ksmbd_file_table *ft,
 		       struct ksmbd_tree_connect *tcon,
fs/smb/server/vfs_cache.h +9 -0
index fcb13413fa8d..03d0bf941216 100644
@@ -60,6 +60,12 @@ struct ksmbd_inode {
 	__le32				m_fattr;
 };
 
+enum {
+	FP_NEW = 0,
+	FP_INITED,
+	FP_CLOSED
+};
+
 struct ksmbd_file {
 	struct file			*filp;
 	u64				persistent_id;

@@ -98,6 +104,7 @@ struct ksmbd_file {
 	/* if ls is happening on directory, below is valid*/
 	struct ksmbd_readdir_data	readdir_data;
 	int				dot_dotdot[2];
+	unsigned int			f_state;
 };
 
 static inline void set_ctx_actor(struct dir_context *ctx,

@@ -142,6 +149,8 @@ int ksmbd_close_inode_fds(struct ksmbd_work *work, struct inode *inode);
 int ksmbd_init_global_file_table(void);
 void ksmbd_free_global_file_table(void);
 void ksmbd_set_fd_limit(unsigned long limit);
+void ksmbd_update_fstate(struct ksmbd_file_table *ft, struct ksmbd_file *fp,
+			 unsigned int state);
 
 /*
  * INODE hash