mtd/ftl: fix the double free of the buffers allocated in build_maps()

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=a152056c912db82860a8b4c23d0bd3a5aa89e363
Commit:     a152056c912db82860a8b4c23d0bd3a5aa89e363
Parent:     c95777a4bb5daca9857157cc18cb7b8d470364aa
Author:     Kevin Hao <haokexin at gmail.com>
AuthorDate: Thu Jul 3 10:35:26 2014 +0800
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Mon Jul 14 18:41:20 2014 -0700

    mtd/ftl: fix the double free of the buffers allocated in build_maps()
    
    I got the following panic on my fsl p5020ds board.
    
      Unable to handle kernel paging request for data at address 0x7375627379737465
      Faulting instruction address: 0xc000000000100778
      Oops: Kernel access of bad area, sig: 11 [#1]
      SMP NR_CPUS=24 CoreNet Generic
      Modules linked in:
      CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.15.0-next-20140613 #145
      task: c0000000fe080000 ti: c0000000fe088000 task.ti: c0000000fe088000
      NIP: c000000000100778 LR: c00000000010073c CTR: 0000000000000000
      REGS: c0000000fe08aa00 TRAP: 0300   Not tainted  (3.15.0-next-20140613)
      MSR: 0000000080029000 <CE,EE,ME>  CR: 24ad2e24  XER: 00000000
      DEAR: 7375627379737465 ESR: 0000000000000000 SOFTE: 1
      GPR00: c0000000000c99b0 c0000000fe08ac80 c0000000009598e0 c0000000fe001d80
      GPR04: 00000000000000d0 0000000000000913 c000000007902b20 0000000000000000
      GPR08: c0000000feaae888 0000000000000000 0000000007091000 0000000000200200
      GPR12: 0000000028ad2e28 c00000000fff4000 c0000000007abe08 0000000000000000
      GPR16: c0000000007ab160 c0000000007aaf98 c00000000060ba68 c0000000007abda8
      GPR20: c0000000007abde8 c0000000feaea6f8 c0000000feaea708 c0000000007abd10
      GPR24: c000000000989370 c0000000008c6228 00000000000041ed c0000000fe00a400
      GPR28: c00000000017c1cc 00000000000000d0 7375627379737465 c0000000fe001d80
      NIP [c000000000100778] .__kmalloc_track_caller+0x70/0x168
      LR [c00000000010073c] .__kmalloc_track_caller+0x34/0x168
      Call Trace:
      [c0000000fe08ac80] [c00000000087e6b8] uevent_sock_list+0x0/0x10 (unreliable)
      [c0000000fe08ad20] [c0000000000c99b0] .kstrdup+0x44/0x90
      [c0000000fe08adc0] [c00000000017c1cc] .__kernfs_new_node+0x4c/0x130
      [c0000000fe08ae70] [c00000000017d7e4] .kernfs_new_node+0x2c/0x64
      [c0000000fe08aef0] [c00000000017db00] .kernfs_create_dir_ns+0x34/0xc8
      [c0000000fe08af80] [c00000000018067c] .sysfs_create_dir_ns+0x58/0xcc
      [c0000000fe08b010] [c0000000002c711c] .kobject_add_internal+0xc8/0x384
      [c0000000fe08b0b0] [c0000000002c7644] .kobject_add+0x64/0xc8
      [c0000000fe08b140] [c000000000355ebc] .device_add+0x11c/0x654
      [c0000000fe08b200] [c0000000002b5988] .add_disk+0x20c/0x4b4
      [c0000000fe08b2c0] [c0000000003a21d4] .add_mtd_blktrans_dev+0x340/0x514
      [c0000000fe08b350] [c0000000003a3410] .mtdblock_add_mtd+0x74/0xb4
      [c0000000fe08b3e0] [c0000000003a32cc] .blktrans_notify_add+0x64/0x94
      [c0000000fe08b470] [c00000000039b5b4] .add_mtd_device+0x1d4/0x368
      [c0000000fe08b520] [c00000000039b830] .mtd_device_parse_register+0xe8/0x104
      [c0000000fe08b5c0] [c0000000003b8408] .of_flash_probe+0x72c/0x734
      [c0000000fe08b750] [c00000000035ba40] .platform_drv_probe+0x38/0x84
      [c0000000fe08b7d0] [c0000000003599a4] .really_probe+0xa4/0x29c
      [c0000000fe08b870] [c000000000359d3c] .__driver_attach+0x100/0x104
      [c0000000fe08b900] [c00000000035746c] .bus_for_each_dev+0x84/0xe4
      [c0000000fe08b9a0] [c0000000003593c0] .driver_attach+0x24/0x38
      [c0000000fe08ba10] [c000000000358f24] .bus_add_driver+0x1c8/0x2ac
      [c0000000fe08bab0] [c00000000035a3a4] .driver_register+0x8c/0x158
      [c0000000fe08bb30] [c00000000035b9f4] .__platform_driver_register+0x6c/0x80
      [c0000000fe08bba0] [c00000000084e080] .of_flash_driver_init+0x1c/0x30
      [c0000000fe08bc10] [c000000000001864] .do_one_initcall+0xbc/0x238
      [c0000000fe08bd00] [c00000000082cdc0] .kernel_init_freeable+0x188/0x268
      [c0000000fe08bdb0] [c0000000000020a0] .kernel_init+0x1c/0xf7c
      [c0000000fe08be30] [c000000000000884] .ret_from_kernel_thread+0x58/0xd4
      Instruction dump:
      41bd0010 480000c8 4bf04eb5 60000000 e94d0028 e93f0000 7cc95214 e8a60008
      7fc9502a 2fbe0000 419e00c8 e93f0022 <7f7e482a> 39200000 88ed06b2 992d06b2
      ---[ end trace b4c9a94804a42d40 ]---
    
    It seems that the corrupted partition header on my mtd device triggers
    a bug in the ftl. In function build_maps() it will allocate the buffers
    needed by the mtd partition, but if something goes wrong such as kmalloc
    failure, mtd read error or invalid partition header parameter, it will
    free all allocated buffers and then return non-zero. In my case, it
    seems that partition header parameter 'NumTransferUnits' is invalid.
    
    And the ftl_freepart() is a function which free all the partition
    buffers allocated by build_maps(). Given the build_maps() is a self
    cleaning function, so there is no need to invoke this function even
    if build_maps() return with error. Otherwise it will causes the
    buffers to be freed twice and then weird things would happen.
    
    Cc: stable at vger.kernel.org
    Signed-off-by: Kevin Hao <haokexin at gmail.com>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/ftl.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/mtd/ftl.c b/drivers/mtd/ftl.c
index 71f2782..dabf084 100644
--- a/drivers/mtd/ftl.c
+++ b/drivers/mtd/ftl.c
@@ -1072,7 +1072,6 @@ static void ftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
 			return;
 	}
 
-	ftl_freepart(partition);
 	kfree(partition);
 }