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From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Colin Ian King <colin.king@canonical.com>,
	Steve French <stfrench@microsoft.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-cifs@vger.kernel.org
Subject: [PATCH AUTOSEL 4.14 02/26] cifs: don't dereference smb_file_target before null check
Date: Tue, 13 Nov 2018 00:51:26 -0500	[thread overview]
Message-ID: <20181113055150.78773-2-sashal@kernel.org> (raw)
In-Reply-To: <20181113055150.78773-1-sashal@kernel.org>

From: Colin Ian King <colin.king@canonical.com>

[ Upstream commit 8c6c9bed8773375b1d54ccca2911ec892c59db5d ]

There is a null check on dst_file->private data which suggests
it can be potentially null. However, before this check, pointer
smb_file_target is derived from dst_file->private and dereferenced
in the call to tlink_tcon, hence there is a potential null pointer
deference.

Fix this by assigning smb_file_target and target_tcon after the
null pointer sanity checks.

Detected by CoverityScan, CID#1475302 ("Dereference before null check")

Fixes: 04b38d601239 ("vfs: pull btrfs clone API to vfs layer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/cifsfs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 44a7b2dea688..c5fd5abf7206 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -933,8 +933,8 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off,
 	struct inode *src_inode = file_inode(src_file);
 	struct inode *target_inode = file_inode(dst_file);
 	struct cifsFileInfo *smb_file_src = src_file->private_data;
-	struct cifsFileInfo *smb_file_target = dst_file->private_data;
-	struct cifs_tcon *target_tcon = tlink_tcon(smb_file_target->tlink);
+	struct cifsFileInfo *smb_file_target;
+	struct cifs_tcon *target_tcon;
 	unsigned int xid;
 	int rc;
 
@@ -948,6 +948,9 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off,
 		goto out;
 	}
 
+	smb_file_target = dst_file->private_data;
+	target_tcon = tlink_tcon(smb_file_target->tlink);
+
 	/*
 	 * Note: cifs case is easier than btrfs since server responsible for
 	 * checks for proper open modes and file type and if it wants
-- 
2.17.1


  reply	other threads:[~2018-11-13  5:51 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-13  5:51 [PATCH AUTOSEL 4.14 01/26] bfs: add sanity check at bfs_fill_super() Sasha Levin
2018-11-13  5:51 ` Sasha Levin [this message]
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 03/26] cifs: fix return value for cifs_listxattr Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 04/26] arm64: kprobe: make page to RO mode when allocate it Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 05/26] nvme-pci: fix conflicting p2p resource adds Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 06/26] ixgbe: fix MAC anti-spoofing filter after VFLR Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 07/26] mm: Fix warning in insert_pfn() Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 08/26] mm/memory_hotplug: make add_memory() take the device_hotplug_lock Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 09/26] reiserfs: propagate errors from fill_with_dentries() properly Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 10/26] hfs: prevent btree data loss on root split Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 11/26] hfsplus: " Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 12/26] um: Give start_idle_thread() a return code Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 13/26] drm/edid: Add 6 bpc quirk for BOE panel Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 14/26] platform/x86: intel_telemetry: report debugfs failure Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 15/26] clk: fixed-rate: fix of_node_get-put imbalance Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 16/26] perf symbols: Set PLT entry/header sizes properly on Sparc Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 17/26] fs/exofs: fix potential memory leak in mount option parsing Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 18/26] clk: samsung: exynos5420: Enable PERIS clocks for suspend Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 19/26] apparmor: Fix uninitialized value in aa_split_fqname Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 20/26] x86/earlyprintk: Add a force option for pciserial device Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 21/26] platform/x86: acerhdf: Add BIOS entry for Gateway LT31 v1.3307 Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 22/26] arm64: percpu: Initialize ret in the default case Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 23/26] mm/vmstat.c: assert that vmstat_text is in sync with stat_items_size Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 24/26] userfaultfd: allow get_mempolicy(MPOL_F_NODE|MPOL_F_ADDR) to trigger userfaults Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 25/26] mm: don't miss the last page because of round-off error Sasha Levin
2018-11-13  5:51 ` [PATCH AUTOSEL 4.14 26/26] mm: don't warn about large allocations for slab Sasha Levin

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