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authorShaun Ruffell <sruffell@digium.com>2012-09-22 20:26:38 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2012-09-23 14:46:40 -0700
commitfaa2ad09c01c48012fe4c117d3256e354e0f9238 (patch)
treeb525fbdc4fa81daec86c6b09de4ee48f009d1934 /drivers/edac
parentef6e7816b4546475d04b4ea22d58c48472157c70 (diff)
downloadlinux-linaro-stable-faa2ad09c01c48012fe4c117d3256e354e0f9238.tar.gz
edac_mc: edac_mc_free() cannot assume mem_ctl_info is registered in sysfs.
Fix potential NULL pointer dereference in edac_unregister_sysfs() on system boot introduced in 3.6-rc1. Since commit 7a623c039 ("edac: rewrite the sysfs code to use struct device") edac_mc_alloc() no longer initializes embedded kobjects in struct mem_ctl_info. Therefore edac_mc_free() can no longer simply decrement a kobject reference count to free the allocated memory unless the memory controller driver module had also called edac_mc_add_mc(). Now edac_mc_free() will check if the newly embedded struct device has been registered with sysfs before using either the standard device release functions or freeing the data structures itself with logic pulled out of the error path of edac_mc_alloc(). The BUG this patch resolves for me: BUG: unable to handle kernel NULL pointer dereference at (null) EIP is at __wake_up_common+0x1a/0x6a Process modprobe (pid: 933, ti=f3dc6000 task=f3db9520 task.ti=f3dc6000) Call Trace: complete_all+0x3f/0x50 device_pm_remove+0x23/0xa2 device_del+0x34/0x142 edac_unregister_sysfs+0x3b/0x5c [edac_core] edac_mc_free+0x29/0x2f [edac_core] e7xxx_probe1+0x268/0x311 [e7xxx_edac] e7xxx_init_one+0x56/0x61 [e7xxx_edac] local_pci_probe+0x13/0x15 ... Cc: Mauro Carvalho Chehab <mchehab@redhat.com> Cc: Shaohui Xie <Shaohui.Xie@freescale.com> Signed-off-by: Shaun Ruffell <sruffell@digium.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/edac')
-rw-r--r--drivers/edac/edac_mc.c59
1 files changed, 39 insertions, 20 deletions
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 9037ffa100d5..d5dc9da7f99f 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 (!device_is_registered(&mci->dev)) {
+ _edac_mc_free(mci);
+ return;
+ }
+
/* the mci instance is freed here, when the sysfs object is dropped */
edac_unregister_sysfs(mci);
}