linux-kernel - [PATCH 3.2 012/152] UBI: Fix invalid vfree()

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Message-ID: <lsq.1424137613.276532024@decadent.org.uk>
Date:	Tue, 17 Feb 2015 01:46:53 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Richard Weinberger" <richard@....at>,
	"Artem Bityutskiy" <artem.bityutskiy@...ux.intel.com>
Subject: [PATCH 3.2 012/152] UBI: Fix invalid vfree()

3.2.67-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Richard Weinberger <richard@....at>

commit f38aed975c0c3645bbdfc5ebe35726e64caaf588 upstream.

The logic of vfree()'ing vol->upd_buf is tied to vol->updating.
In ubi_start_update() vol->updating is set long before vmalloc()'ing
vol->upd_buf. If we encounter a write failure in ubi_start_update()
before vmalloc() the UBI device release function will try to vfree()
vol->upd_buf because vol->updating is set.
Fix this by allocating vol->upd_buf directly after setting vol->updating.

Fixes:
[   31.559338] UBI warning: vol_cdev_release: update of volume 2 not finished, volume is damaged
[   31.559340] ------------[ cut here ]------------
[   31.559343] WARNING: CPU: 1 PID: 2747 at mm/vmalloc.c:1446 __vunmap+0xe3/0x110()
[   31.559344] Trying to vfree() nonexistent vm area (ffffc90001f2b000)
[   31.559345] Modules linked in:
[   31.565620]  0000000000000bba ffff88002a0cbdb0 ffffffff818f0497 ffff88003b9ba148
[   31.566347]  ffff88002a0cbde0 ffffffff8156f515 ffff88003b9ba148 0000000000000bba
[   31.567073]  0000000000000000 0000000000000000 ffff88002a0cbe88 ffffffff8156c10a
[   31.567793] Call Trace:
[   31.568034]  [<ffffffff818f0497>] dump_stack+0x4e/0x7a
[   31.568510]  [<ffffffff8156f515>] ubi_io_write_vid_hdr+0x155/0x160
[   31.569084]  [<ffffffff8156c10a>] ubi_eba_write_leb+0x23a/0x870
[   31.569628]  [<ffffffff81569b36>] vol_cdev_write+0x226/0x380
[   31.570155]  [<ffffffff81179265>] vfs_write+0xb5/0x1f0
[   31.570627]  [<ffffffff81179f8a>] SyS_pwrite64+0x6a/0xa0
[   31.571123]  [<ffffffff818fde12>] system_call_fastpath+0x16/0x1b

Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mtd/ubi/upd.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/mtd/ubi/upd.c
+++ b/drivers/mtd/ubi/upd.c
@@ -135,6 +135,10 @@ int ubi_start_update(struct ubi_device *
 	ubi_assert(!vol->updating && !vol->changing_leb);
 	vol->updating = 1;
 
+	vol->upd_buf = vmalloc(ubi->leb_size);
+	if (!vol->upd_buf)
+		return -ENOMEM;
+
 	err = set_update_marker(ubi, vol);
 	if (err)
 		return err;
@@ -154,14 +158,12 @@ int ubi_start_update(struct ubi_device *
 		err = clear_update_marker(ubi, vol, 0);
 		if (err)
 			return err;
+
+		vfree(vol->upd_buf);
 		vol->updating = 0;
 		return 0;
 	}
 
-	vol->upd_buf = vmalloc(ubi->leb_size);
-	if (!vol->upd_buf)
-		return -ENOMEM;
-
 	vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
 			       vol->usable_leb_size);
 	vol->upd_bytes = bytes;

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