[PATCH] Fix smbd panic if we chdir() to an unreadable directory.

[Ralph Böhme]

Howdy!

On Fri, Oct 06, 2017 at 09:56:50PM +0000, Jeremy Allison wrote:
> Please review and push if happy.

generally looks good, but, while at it, can we use an early return and reduce the
indentation level please?

-slow
-------------- next part --------------
From cae435c8a948c1a39ab750aba24fe749e79601a2 Mon Sep 17 00:00:00 2001
From: Ralph Boehme <slow at samba.org>
Date: Sun, 8 Oct 2017 18:48:23 +0200
Subject: [PATCH] FIXUP: early return from failing SMB_VFS_CHDIR, reducing
 indentation level

---
 source3/smbd/vfs.c | 92 +++++++++++++++++++++++++++++-------------------------
 1 file changed, 49 insertions(+), 43 deletions(-)

diff --git a/source3/smbd/vfs.c b/source3/smbd/vfs.c
index 817e69b484b..d4fccb7eda9 100644
--- a/source3/smbd/vfs.c
+++ b/source3/smbd/vfs.c
@@ -888,57 +888,63 @@ int vfs_ChDir(connection_struct *conn, const struct smb_filename *smb_fname)
 	DEBUG(4,("vfs_ChDir to %s\n", smb_fname->base_name));
 
 	ret = SMB_VFS_CHDIR(conn, smb_fname);
-	if (ret == 0) {
+	if (ret != 0) {
+		saved_errno = errno;
+		TALLOC_FREE(saved_cwd);
+		errno = saved_errno;
+		return -1;
+	}
+
+	/*
+	 * Always replace conn->cwd_fname. We
+	 * don't know if it's been modified by
+	 * VFS modules in the stack.
+	 */
+
+	/* conn cache. */
+	TALLOC_FREE(conn->cwd_fname);
+	conn->cwd_fname = vfs_GetWd(conn, conn);
+	if (conn->cwd_fname == NULL) {
 		/*
-		 * Always replace conn->cwd_fname. We
-		 * don't know if it's been modified by
-		 * VFS modules in the stack.
+		 * vfs_GetWd() failed.
+		 * We must be able to read cwd.
+		 * Return to original directory
+		 * and return -1.
 		 */
-		/* conn cache. */
-		TALLOC_FREE(conn->cwd_fname);
-		conn->cwd_fname = vfs_GetWd(conn, conn);
-		if (conn->cwd_fname == NULL) {
+		saved_errno = errno;
+
+		if (saved_cwd == NULL) {
 			/*
-			 * vfs_GetWd() failed.
-			 * We must be able to read cwd.
-			 * Return to original directory
-			 * and return -1.
+			 * Failed on the very first chdir()+getwd()
+			 * for this connection. We can't
+			 * continue.
 			 */
-			saved_errno = errno;
-
-			if (saved_cwd == NULL) {
-				/*
-				 * Failed on the very first chdir()+getwd()
-				 * for this connection. We can't
-				 * continue.
-				 */
-				smb_panic("conn->cwd getwd failed\n");
-				/* NOTREACHED */
-				return -1;
-			}
-
-			/* Return to the previous $cwd. */
-			ret = SMB_VFS_CHDIR(conn, saved_cwd);
-			if (ret != 0) {
-				smb_panic("conn->cwd getwd failed\n");
-				/* NOTREACHED */
-				return -1;
-			}
-			/* Restore original conn->cwd_fname. */
-			conn->cwd_fname = saved_cwd;
-			errno = saved_errno;
-			/* And fail the chdir(). */
+			smb_panic("conn->cwd getwd failed\n");
+			/* NOTREACHED */
 			return -1;
 		}
-		/* vfs_GetWd() succeeded. */
-		/* Replace global cache. */
-		SAFE_FREE(LastDir);
-		LastDir = SMB_STRDUP(smb_fname->base_name);
 
-		DEBUG(4,("vfs_ChDir got %s\n", conn->cwd_fname->base_name));
-	} else {
-		saved_errno = errno;
+		/* Return to the previous $cwd. */
+		ret = SMB_VFS_CHDIR(conn, saved_cwd);
+		if (ret != 0) {
+			smb_panic("conn->cwd getwd failed\n");
+			/* NOTREACHED */
+			return -1;
+		}
+		/* Restore original conn->cwd_fname. */
+		conn->cwd_fname = saved_cwd;
+		errno = saved_errno;
+		/* And fail the chdir(). */
+		return -1;
 	}
+
+	/* vfs_GetWd() succeeded. */
+	/* Replace global cache. */
+	SAFE_FREE(LastDir);
+	LastDir = SMB_STRDUP(smb_fname->base_name);
+
+	DEBUG(4,("vfs_ChDir got %s\n", conn->cwd_fname->base_name));
+
 	TALLOC_FREE(saved_cwd);
 	if (saved_errno != 0) {
 		errno = saved_errno;
-- 
2.13.5