[PATCH 4.4 18/69] ubifs: Abort readdir upon error

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 4.4 18/69] ubifs: Abort readdir upon error
Date	2016-11-09 11:50 +0100
Message-ID	<sByC6-69v-67@gated-at.bofh.it> (permalink)
References	<sByC5-69v-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Weinberger <richard@nod.at>

commit c83ed4c9dbb358b9e7707486e167e940d48bfeed upstream.

If UBIFS is facing an error while walking a directory, it reports this
error and ubifs_readdir() returns the error code. But the VFS readdir
logic does not make the getdents system call fail in all cases. When the
readdir cursor indicates that more entries are present, the system call
will just return and the libc wrapper will try again since it also
knows that more entries are present.
This causes the libc wrapper to busy loop for ever when a directory is
corrupted on UBIFS.
A common approach do deal with corrupted directory entries is
skipping them by setting the cursor to the next entry. On UBIFS this
approach is not possible since we cannot compute the next directory
entry cursor position without reading the current entry. So all we can
do is setting the cursor to the "no more entries" position and make
getdents exit.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ubifs/dir.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -350,7 +350,7 @@ static unsigned int vfs_dent_type(uint8_
  */
 static int ubifs_readdir(struct file *file, struct dir_context *ctx)
 {
-	int err;
+	int err = 0;
 	struct qstr nm;
 	union ubifs_key key;
 	struct ubifs_dent_node *dent;
@@ -452,14 +452,12 @@ out:
 	kfree(file->private_data);
 	file->private_data = NULL;
 
-	if (err != -ENOENT) {
+	if (err != -ENOENT)
 		ubifs_err(c, "cannot find next direntry, error %d", err);
-		return err;
-	}
 
 	/* 2 is a special value indicating that there are no more direntries */
 	ctx->pos = 2;
-	return 0;
+	return err;
 }
 
 /* Free saved readdir() state when the directory is closed */

Thread

[PATCH 4.4 00/69] 4.4.31-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 23/69] USB: serial: ftdi_sio: add support for Infineon TriBoard TC2X7 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 27/69] Fix potential infoleak in older kernels Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 32/69] USB: serial: cp210x: fix tiocmget error handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 04/69] h8300: fix syscall restarting Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 01/69] i2c: xgene: Avoid dma_buffer overrun Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 19/69] ubifs: Fix regression in ubifs_readdir() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 29/69] hv: do not lose pending heartbeat vmbus packets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 31/69] tty: limit terminal size to 4M chars Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 11/69] ALSA: hda - Raise AZX_DCAPS_RIRB_DELAY handling into top drivers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 06/69] mm/list_lru.c: avoid error-path NULL pointer deref Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 20/69] mei: txe: dont clean an unprocessed interrupt cause. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 22/69] USB: serial: fix potential NULL-dereference at probe Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 18/69] ubifs: Abort readdir upon error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 26/69] GenWQE: Fix bad page access during abort of resource allocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 11:50 +0100
  [PATCH 4.4 08/69] KEYS: Fix short sprintf buffer in /proc/keys show function Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:00 +0100
  [PATCH 4.4 02/69] i2c: core: fix NULL pointer dereference under race condition Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:00 +0100
  [PATCH 4.4 07/69] mm: memcontrol: do not recurse in direct reclaim Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:00 +0100
  [PATCH 4.4 67/69] kvm: x86: Check memopp before dereference (CVE-2016-8630) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 60/69] cgroup: avoid false positive gcc-6 warning Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 37/69] parisc: Ensure consistent state when switching to kernel stack at syscall entry Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 46/69] scsi: scsi_debug: Fix memory leak if LBP enabled and module is unloaded Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 39/69] virtio: console: Unlock vqs while freeing buffers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 47/69] scsi: arcmsr: Send SYNCHRONIZE_CACHE command to firmware Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 65/69] usb: dwc3: Fix size used in dma_free_coherent() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 54/69] perf build: Fix traceevent plugins build race Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 38/69] virtio_ring: Make interrupt suppression spec compliant Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 57/69] ARM: 8584/1: floppy: avoid gcc-6 warning Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 51/69] drm/radeon/si_dpm: workaround for SI kickers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 64/69] pwm: Unexport children before chip removal Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 36/69] ovl: fsync after copy-up Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 42/69] firewire: net: guard against rx buffer overflows Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:10 +0100
  [PATCH 4.4 68/69] ubi: fastmap: Fix add_vol() return value test in ubi_attach_fastmap() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:40 +0100
  [PATCH 4.4 44/69] mac80211: discard multicast and 4-addr A-MSDUs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:40 +0100
  [PATCH 4.4 43/69] firewire: net: fix fragmented datagram_size off-by-one Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:40 +0100
  [PATCH 4.4 45/69] scsi: megaraid_sas: Fix data integrity failure for JBOD (passthrough) devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:40 +0100
  [PATCH 4.4 69/69] HID: usbhid: add ATEN CS962 to list of quirky devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:40 +0100
  [PATCH 4.4 50/69] drm/radeon/si_dpm: Limit clocks on HD86xx part Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 58/69] mm/cma: silence warnings due to max() usage Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 59/69] drm/exynos: fix error handling in exynos_drm_subdrv_open Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 41/69] Input: i8042 - add XMG C504 to keyboard reset table Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 48/69] mmc: dw_mmc-pltfm: fix the potential NULL pointer dereference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 63/69] UBI: fastmap: scrub PEB when bitflips are detected in a free PEB EC header Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 55/69] x86/xen: fix upper bound of pmd loop in xen_cleanhighmap() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 56/69] powerpc/ptrace: Fix out of bounds array access warning Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 40/69] dm mirror: fix read error on recovery after default leg failure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  [PATCH 4.4 61/69] smc91x: avoid self-comparison warning Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 12:50 +0100
  Re: [PATCH 4.4 00/69] 4.4.31-stable review Shuah Khan <shuah.kh@samsung.com> - 2016-11-09 19:30 +0100
  Re: [PATCH 4.4 00/69] 4.4.31-stable review Guenter Roeck <linux@roeck-us.net> - 2016-11-09 20:40 +0100

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