This is a note to let you know that I've just added the patch titled
ksmbd: fix race condition with fp
to the 6.1-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:
ksmbd-fix-race-condition-with-fp.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b57845f40f0bba8a4b103274bc0d12a861038b48
Author: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Date: Sun Dec 31 16:13:04 2023 +0900
ksmbd: fix race condition with fp
[ Upstream commit 5a7ee91d1154f35418367a6eaae74046fd06ed89 ]
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 <rootlab@xxxxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 42697ea86d47b..d5bf1f480700a 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -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;
diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c
index 94ad8fa07b46e..f600279b0a9ee 100644
--- a/fs/smb/server/vfs_cache.c
+++ b/fs/smb/server/vfs_cache.c
@@ -332,6 +332,9 @@ 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;
@@ -381,15 +384,20 @@ 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;
@@ -569,6 +577,7 @@ 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) {
@@ -590,6 +599,14 @@ 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,
diff --git a/fs/smb/server/vfs_cache.h b/fs/smb/server/vfs_cache.h
index fcb13413fa8d9..03d0bf941216f 100644
--- a/fs/smb/server/vfs_cache.h
+++ b/fs/smb/server/vfs_cache.h
@@ -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
