Subject: possible double free in edac_mc_alloc()
Reply-To:
User-Agent: Heirloom mailx 12.5 6/20/10
Hi,
coccinelle warns about:
+ drivers/edac/edac_mc.c:429:9-23: ERROR: reference preceded by free on line 429
and that line does look strange: the 'i' seems like a temporary value
used in previous loops, and it won't change at all in the current
loop. Which means the same mci->csrows[i] get freed once and again.
It might also do double free for the previous kfree(csr) line.
vim +429 drivers/edac/edac_mc.c
416 if (mci->dimms) {
417 for (i = 0; i < tot_dimms; i++)
418 kfree(mci->dimms[i]);
419 kfree(mci->dimms);
420 }
421 if (mci->csrows) {
422 for (chn = 0; chn < tot_channels; chn++) {
423 csr = mci->csrows[chn];
424 if (csr) {
425 for (chn = 0; chn < tot_channels; chn++)
426 kfree(csr->channels[chn]);
427 kfree(csr);
428 }
> 429 kfree(mci->csrows[i]);
430 }
431 kfree(mci->csrows);
432 }
---
0-DAY kernel build testing backend Open Source Technology Centre
Fengguang Wu <[email protected]> Intel Corporation
Hi Fengguang,
Em 09-08-2012 10:54, Fengguang Wu escreveu:
...
> Date: Thu, 9 Aug 2012 21:54:16 +0800
> From: Fengguang Wu <[email protected]>
> To: Mauro Carvalho Chehab <[email protected]>
> Cc: Dave Peterson <[email protected]>, [email protected],
> Doug Thompson <[email protected]>, [email protected],
> [email protected]
> Message-ID: <20120809135416.GA13100@localhost>
> MIME-Version: 1.0
> Content-Type: text/plain; charset=us-ascii
> Content-Disposition: inline
> User-Agent: Mutt/1.5.21 (2010-09-15)
> X-RedHat-Spam-Score: -5.111 (BAYES_00,MISSING_SUBJECT,RCVD_IN_DNSWL_HI,T_RP_MATCHES_RCVD)
> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24
> X-Scanned-By: MIMEDefang 2.68 on 10.5.110.17
>
> Subject: possible double free in edac_mc_alloc()
> Reply-To:
> User-Agent: Heirloom mailx 12.5 6/20/10
There is an extra space between the email headers and the Subject...
due to that I almost deleted this message, considering it as spam.
>
> Hi,
>
> coccinelle warns about:
>
> + drivers/edac/edac_mc.c:429:9-23: ERROR: reference preceded by free on line 429
>
> and that line does look strange: the 'i' seems like a temporary value
> used in previous loops, and it won't change at all in the current
> loop. Which means the same mci->csrows[i] get freed once and again.
> It might also do double free for the previous kfree(csr) line.
>
> vim +429 drivers/edac/edac_mc.c
>
> 416 if (mci->dimms) {
> 417 for (i = 0; i < tot_dimms; i++)
> 418 kfree(mci->dimms[i]);
> 419 kfree(mci->dimms);
> 420 }
> 421 if (mci->csrows) {
> 422 for (chn = 0; chn < tot_channels; chn++) {
> 423 csr = mci->csrows[chn];
> 424 if (csr) {
> 425 for (chn = 0; chn < tot_channels; chn++)
> 426 kfree(csr->channels[chn]);
> 427 kfree(csr);
> 428 }
> > 429 kfree(mci->csrows[i]);
It should likely be:
kfree(mci->csrows[csr])
instead. This is likely due to one of the countless rebases I had to do on it,
in order to make everybody happy. I suspect that, in the past, this loop was also
using 'i' as the index variable.
Care to write us a patch fixing it? My HD crashed yesterday... I'm somewhat
busy today recovering from it, and doing some backup/restore stuff.
Thanks!
Mauro
> 430 }
> 431 kfree(mci->csrows);
> 432 }
>
> ---
> 0-DAY kernel build testing backend Open Source Technology Centre
> Fengguang Wu <[email protected]> Intel Corporation
>
We need to free up memory in this order:
free csrows[i]->channels[j]
free csrows[i]->channels
free csrows[i]
free csrows
Signed-off-by: Fengguang Wu <[email protected]>
---
drivers/edac/edac_mc.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- linux.orig/drivers/edac/edac_mc.c 2012-08-10 17:16:14.444794060 +0800
+++ linux/drivers/edac/edac_mc.c 2012-08-10 17:16:19.048794169 +0800
@@ -419,14 +419,16 @@ error:
kfree(mci->dimms);
}
if (mci->csrows) {
- for (chn = 0; chn < tot_channels; chn++) {
- csr = mci->csrows[chn];
+ for (row = 0; row < tot_csrows; row++) {
+ csr = mci->csrows[row];
if (csr) {
- for (chn = 0; chn < tot_channels; chn++)
- kfree(csr->channels[chn]);
+ if (csr->channels) {
+ for (chn = 0; chn < tot_channels; chn++)
+ kfree(csr->channels[chn]);
+ kfree(csr->channels);
+ }
kfree(csr);
}
- kfree(mci->csrows[i]);
}
kfree(mci->csrows);
}
From: Fengguang Wu <[email protected]>
We need to free up memory in this order:
free csrows[i]->channels[j]
free csrows[i]->channels
free csrows[i]
free csrows
Signed-off-by: Fengguang Wu <[email protected]>
---
drivers/edac/edac_mc.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 616d90b..9037ffa 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -419,14 +419,16 @@ error:
kfree(mci->dimms);
}
if (mci->csrows) {
- for (chn = 0; chn < tot_channels; chn++) {
- csr = mci->csrows[chn];
+ for (row = 0; row < tot_csrows; row++) {
+ csr = mci->csrows[row];
if (csr) {
- for (chn = 0; chn < tot_channels; chn++)
- kfree(csr->channels[chn]);
+ if (csr->channels) {
+ for (chn = 0; chn < tot_channels; chn++)
+ kfree(csr->channels[chn]);
+ kfree(csr->channels);
+ }
kfree(csr);
}
- kfree(mci->csrows[i]);
}
kfree(mci->csrows);
}
--
1.7.11.2
edac_mc_free() may need to deallocate any memory associated with struct
mem_ctl_info directly if the structure was never registered with sysfs in
edac_mc_add_mc(). This moves the error handling code from edac_mc_alloc() into a
dedicated function to be called by edac_mc_free() as well if necessary.
This resolves a NULL pointer dereference from the following code path first
introduced in 3.6-rc1:
EDAC MC: Ver: 3.0.0
EDAC DEBUG: edac_mc_sysfs_init: device mc created
EDAC DEBUG: e7xxx_init_one:
EDAC DEBUG: e7xxx_probe1: mci
EDAC DEBUG: edac_mc_alloc: errcount layer 0 size 8
EDAC DEBUG: edac_mc_alloc: errcount layer 1 size 16
EDAC DEBUG: edac_mc_alloc: allocating 48 error counters
EDAC DEBUG: edac_mc_alloc: allocating 1068 bytes for mci data (16 ranks, 16 csrows/channels)
EDAC DEBUG: e7xxx_probe1: init mci
EDAC DEBUG: e7xxx_probe1: init pvt
EDAC e7xxx: error reporting device not found:vendor 8086 device 0x2541 (broken BIOS?)
EDAC DEBUG: edac_mc_free:
Floppy drive(s): fd0 is 1.44M
EDAC DEBUG: edac_unregister_sysfs: Unregistering device (null)
Signed-off-by: Shaun Ruffell <[email protected]>
---
drivers/edac/edac_mc.c | 59 +++++++++++++++++++++++++++++++++-----------------
1 file changed, 39 insertions(+), 20 deletions(-)
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 9037ffa..a58facc 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -199,6 +199,36 @@ void *edac_align_ptr(void **p, unsigned size, int n_elems)
return (void *)(((unsigned long)ptr) + align - r);
}
+static void _edac_mc_free(struct mem_ctl_info *mci)
+{
+ int i, chn, row;
+ struct csrow_info *csr;
+ const unsigned int tot_dimms = mci->tot_dimms;
+ const unsigned int tot_channels = mci->num_cschannel;
+ const unsigned int tot_csrows = mci->nr_csrows;
+
+ if (mci->dimms) {
+ for (i = 0; i < tot_dimms; i++)
+ kfree(mci->dimms[i]);
+ kfree(mci->dimms);
+ }
+ if (mci->csrows) {
+ for (row = 0; row < tot_csrows; row++) {
+ csr = mci->csrows[row];
+ if (csr) {
+ if (csr->channels) {
+ for (chn = 0; chn < tot_channels; chn++)
+ kfree(csr->channels[chn]);
+ kfree(csr->channels);
+ }
+ kfree(csr);
+ }
+ }
+ kfree(mci->csrows);
+ }
+ kfree(mci);
+}
+
/**
* edac_mc_alloc: Allocate and partially fill a struct mem_ctl_info structure
* @mc_num: Memory controller number
@@ -413,26 +443,7 @@ struct mem_ctl_info *edac_mc_alloc(unsigned mc_num,
return mci;
error:
- if (mci->dimms) {
- for (i = 0; i < tot_dimms; i++)
- kfree(mci->dimms[i]);
- kfree(mci->dimms);
- }
- if (mci->csrows) {
- for (row = 0; row < tot_csrows; row++) {
- csr = mci->csrows[row];
- if (csr) {
- if (csr->channels) {
- for (chn = 0; chn < tot_channels; chn++)
- kfree(csr->channels[chn]);
- kfree(csr->channels);
- }
- kfree(csr);
- }
- }
- kfree(mci->csrows);
- }
- kfree(mci);
+ _edac_mc_free(mci);
return NULL;
}
@@ -447,6 +458,14 @@ void edac_mc_free(struct mem_ctl_info *mci)
{
edac_dbg(1, "\n");
+ /* If we're not yet registered with sysfs free only what was allocated
+ * in edac_mc_alloc().
+ */
+ if (!mci->bus.name) {
+ _edac_mc_free(mci);
+ return;
+ }
+
/* the mci instance is freed here, when the sysfs object is dropped */
edac_unregister_sysfs(mci);
}
--
1.7.11.2
There are no more embedded kobjects in struct mem_ctl_info. Remove a header and
a comment that does not reflect the code anymore.
Signed-off-by: Shaun Ruffell <[email protected]>
---
drivers/edac/edac_mc.c | 7 -------
include/linux/edac.h | 1 -
2 files changed, 8 deletions(-)
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index a58facc..65c59b1 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -433,13 +433,6 @@ struct mem_ctl_info *edac_mc_alloc(unsigned mc_num,
mci->op_state = OP_ALLOC;
- /* at this point, the root kobj is valid, and in order to
- * 'free' the object, then the function:
- * edac_mc_unregister_sysfs_main_kobj() must be called
- * which will perform kobj unregistration and the actual free
- * will occur during the kobject callback operation
- */
-
return mci;
error:
diff --git a/include/linux/edac.h b/include/linux/edac.h
index bab9f84..aeddb3f 100644
--- a/include/linux/edac.h
+++ b/include/linux/edac.h
@@ -14,7 +14,6 @@
#include <linux/atomic.h>
#include <linux/device.h>
-#include <linux/kobject.h>
#include <linux/completion.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
--
1.7.11.2
With kernel version 3.6-rc2 on a Dell Poweredge 2600 I experienced a NULL
pointer dereference that did not occur with on 3.5. I believe the error is
related to commit de3910eb79a "edac: change the mem allocation scheme to make
Documentation/kobject.txt happy" [1] and the fact that my system is going
through an error path in the e7xxx_edac driver.
[1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=de3910eb79ac8c0f29a11224661c0ebaaf813039
This is the OOPS:
[ 36.703479] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 36.703479] IP: [<c045e195>] __wake_up_common+0x1a/0x6a
[ 36.703479] *pde = 7f0c6067
[ 36.703479] Oops: 0000 [#1] SMP
[ 36.703479] Modules linked in: parport_pc parport floppy e7xxx_edac(+) ide_cd_mod edac_core intel_rng cdrom microcode(+) dm_snapshot dm_zero dm_mirror dm_region_hash d
[ 36.703479] Pid: 933, comm: modprobe Tainted: G W 3.6.0-rc2-00111-gc1999ee #12 Dell Computer Corporation PowerEdge 2600 /0F0364
[ 36.703479] EIP: 0060:[<c045e195>] EFLAGS: 00010093 CPU: 3
[ 36.703479] EIP is at __wake_up_common+0x1a/0x6a
[ 36.703479] EAX: f47b0984 EBX: fffffff4 ECX: 00000000 EDX: 00000003
[ 36.703479] ESI: f47b0984 EDI: 00000282 EBP: f3dc7d38 ESP: f3dc7d1c
[ 36.703479] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[ 36.703479] CR0: 8005003b CR2: 00000000 CR3: 347d4000 CR4: 000007d0
[ 36.703479] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[ 36.703479] DR6: ffff0ff0 DR7: 00000400
[ 36.703479] Process modprobe (pid: 933, ti=f3dc6000 task=f3db9520 task.ti=f3dc6000)
[ 36.703479] Stack:
[ 36.703479] 00000000 00000000 00000003 c046701a f47b0980 f47b0984 00000282 f3dc7d54
[ 36.703479] c046703f 00000000 00000000 f47b08b0 f47b08b0 00000000 f3dc7d74 c06961ce
[ 36.703479] f3dc7d74 f3dc7d80 c05e2837 c094c4cc f47b08b0 f47b08b0 f3dc7d88 c068d56d
[ 36.703479] Call Trace:
[ 36.703479] [<c046701a>] ? complete_all+0x1a/0x50
[ 36.703479] [<c046703f>] complete_all+0x3f/0x50
[ 36.703479] [<c06961ce>] device_pm_remove+0x23/0xa2
[ 36.703479] [<c05e2837>] ? kobject_put+0x5b/0x5d
[ 36.703479] [<c068d56d>] device_del+0x34/0x142
[ 36.703479] [<f8547884>] edac_unregister_sysfs+0x3b/0x5c [edac_core]
[ 36.703479] [<f8545041>] edac_mc_free+0x29/0x2f [edac_core]
[ 36.703479] [<f860163f>] e7xxx_probe1+0x268/0x311 [e7xxx_edac]
[ 36.703479] [<c0603d00>] ? __pci_enable_device_flags+0x8f/0xd3
[ 36.703479] [<f8601b0b>] e7xxx_init_one+0x56/0x61 [e7xxx_edac]
[ 36.703479] [<c0604f85>] local_pci_probe+0x13/0x15
[ 36.703479] [<c0605115>] pci_call_probe+0x1c/0x1e
[ 36.703479] [<c0605158>] __pci_device_probe+0x41/0x4e
[ 36.703479] [<c060579c>] pci_device_probe+0x26/0x39
[ 36.703479] [<c06901ed>] really_probe+0x101/0x2a1
[ 36.703479] [<c0690680>] ? __driver_attach+0x3d/0x6e
[ 36.703479] [<c0690680>] ? __driver_attach+0x3d/0x6e
[ 36.703479] [<c07e0000>] ? quirk_usb_disable_ehci+0xa3/0x141
[ 36.703479] [<c06903c2>] driver_probe_device+0x35/0x79
[ 36.703479] [<c06906af>] __driver_attach+0x6c/0x6e
[ 36.703479] [<c068eb25>] bus_for_each_dev+0x44/0x62
[ 36.703479] [<c068ff00>] driver_attach+0x1e/0x20
[ 36.703479] [<c0690643>] ? device_attach+0x98/0x98
[ 36.703479] [<c068fa12>] bus_add_driver+0xc5/0x1c8
[ 36.703479] [<c0605beb>] ? store_new_id+0xfa/0xfa
[ 36.703479] [<c0690bfb>] driver_register+0x52/0xd6
[ 36.703479] [<f8604000>] ? 0xf8603fff
[ 36.703479] [<c0605a30>] __pci_register_driver+0x4b/0x73
[ 36.703479] [<f8604000>] ? 0xf8603fff
[ 36.703479] [<f8604055>] e7xxx_init+0x55/0x57 [e7xxx_edac]
[ 36.703479] [<c040120e>] do_one_initcall+0xa3/0xe0
[ 36.703479] [<c0491023>] sys_init_module+0x70/0x1af
[ 36.703479] [<c04823a9>] ? trace_hardirqs_on_caller+0x56/0xf9
[ 36.703479] [<c05ec7e8>] ? trace_hardirqs_on_thunk+0xc/0x10
[ 36.703479] [<c07f678c>] sysenter_do_call+0x12/0x32
[ 36.703479] Code: 5d c3 55 89 e5 3e 8d 74 26 00 e8 8f ff ff ff 5d c3 55 89 e5 57 56 53 83 ec 10 3e 8d 74 26 00 89 55 ec 89 4d e8 8b 58 28 83 eb 0c <8b> 53 0c 83 c0 28
[ 36.703479] EIP: [<c045e195>] __wake_up_common+0x1a/0x6a SS:ESP 0068:f3dc7d1c
[ 36.703479] CR2: 0000000000000000
[ 36.703479] ---[ end trace 6fcfddc0eef7bbd8 ]---
When I enabled edac debugging I saw the following printed to the kernel log
prior to the above BUG:
EDAC MC: Ver: 3.0.0
EDAC DEBUG: edac_mc_sysfs_init: device mc created
EDAC DEBUG: e7xxx_init_one:
EDAC DEBUG: e7xxx_probe1: mci
EDAC DEBUG: edac_mc_alloc: errcount layer 0 size 8
EDAC DEBUG: edac_mc_alloc: errcount layer 1 size 16
EDAC DEBUG: edac_mc_alloc: allocating 48 error counters
EDAC DEBUG: edac_mc_alloc: allocating 1068 bytes for mci data (16 ranks, 16 csrows/channels)
EDAC DEBUG: e7xxx_probe1: init mci
EDAC DEBUG: e7xxx_probe1: init pvt
EDAC e7xxx: error reporting device not found:vendor 8086 device 0x2541 (broken BIOS?)
EDAC DEBUG: edac_mc_free:
Floppy drive(s): fd0 is 1.44M
EDAC DEBUG: edac_unregister_sysfs: Unregistering device (null)
There are probably better ways to accomplish what the following patches are
doing but I thought I would send along what I had if only to motivate any
discussion. I also have resent Fengguang Wu's patch in this series since I found
that it was required as well.
Shaun Ruffell (2):
edac: Remove invalid kfree in error path of edac_mc_allocate().
edac: edac_mc_free() cannot assume mem_ctl_info is registered in
sysfs.
drivers/edac/edac_mc.c | 60 +++++++++++++++++++++++++++++---------------------
1 file changed, 35 insertions(+), 25 deletions(-)
--
1.7.11.2