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Subject[PATCH 2/3] edac: edac_mc_free() cannot assume mem_ctl_info is registered in sysfs.
Date
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 <sruffell@digium.com>
---
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


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