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EDAC, amd64_edac: Prevent OOPS with >16 memory controllers
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When DRAM errors occur on memory controllers after EDAC_MAX_MCS (16),
the kernel fatally dereferences unallocated structures, see splat below;
this occurs on at least NumaConnect systems.

Fix by checking if a memory controller info structure was found.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000320
IP: [<ffffffff819f714f>] decode_bus_error+0x2f/0x2b0
PGD 2f8b5a3067 PUD 2f8b5a2067 PMD 0
Oops: 0000 [#2] SMP
Modules linked in:
CPU: 224 PID: 11930 Comm: stream_c.exe.gn Tainted: G   D    3.19.0 #1
Hardware name: Supermicro H8QGL/H8QGL, BIOS 3.5b    01/28/2015
task: ffff8807dbfb8c00 ti: ffff8807dd16c000 task.ti: ffff8807dd16c000
RIP: 0010:[<ffffffff819f714f>] [<ffffffff819f714f>] decode_bus_error+0x2f/0x2b0
RSP: 0000:ffff8907dfc03c48 EFLAGS: 00010297
RAX: 0000000000000001 RBX: 9c67400010080a13 RCX: 0000000000001dc6
RDX: 000000001dc61dc6 RSI: ffff8907dfc03df0 RDI: 000000000000001c
RBP: ffff8907dfc03ce8 R08: 0000000000000000 R09: 0000000000000022
R10: ffff891fffa30380 R11: 00000000001cfc90 R12: 0000000000000008
R13: 0000000000000000 R14: 000000000000001c R15: 00009c6740001000
FS: 00007fa97ee18700(0000) GS:ffff8907dfc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000320 CR3: 0000003f889b8000 CR4: 00000000000407e0
Stack:
 0000000000000000 ffff8907dfc03df0 0000000000000008 9c67400010080a13
 000000000000001c 00009c6740001000 ffff8907dfc03c88 ffffffff810e4f9a
 ffff8907dfc03ce8 ffffffff81b375b9 0000000000000000 0000000000000010
Call Trace:
 <IRQ>
 ? vprintk_default
 ? printk
 amd_decode_mce
 notifier_call_chain
 atomic_notifier_call_chain
 mce_log
 machine_check_poll
 mce_timer_fn
 ? mce_cpu_restart
 call_timer_fn.isra.29
 run_timer_softirq
 __do_softirq
 irq_exit
 smp_apic_timer_interrupt
 apic_timer_interrupt
 <EOI>
 ? down_read_trylock
 __do_page_fault
 ? __schedule
 do_page_fault
 page_fault

Signed-off-by: Daniel J Blueman <daniel@numascale.com>
Link: http://lkml.kernel.org/r/1424144078-24589-1-git-send-email-daniel@numascale.com
Cc: stable@vger.kernel.org
[ Boris: massage commit message ]
Signed-off-by: Borislav Petkov <bp@suse.de>
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dblueman authored and suryasaimadhu committed Feb 17, 2015
1 parent 11249e7 commit 0c510cc
Showing 1 changed file with 8 additions and 2 deletions.
10 changes: 8 additions & 2 deletions drivers/edac/amd64_edac.c
Original file line number Diff line number Diff line change
Expand Up @@ -2174,14 +2174,20 @@ static void __log_bus_error(struct mem_ctl_info *mci, struct err_info *err,

static inline void decode_bus_error(int node_id, struct mce *m)
{
struct mem_ctl_info *mci = mcis[node_id];
struct amd64_pvt *pvt = mci->pvt_info;
struct mem_ctl_info *mci;
struct amd64_pvt *pvt;
u8 ecc_type = (m->status >> 45) & 0x3;
u8 xec = XEC(m->status, 0x1f);
u16 ec = EC(m->status);
u64 sys_addr;
struct err_info err;

mci = edac_mc_find(node_id);
if (!mci)
return;

pvt = mci->pvt_info;

/* Bail out early if this was an 'observed' error */
if (PP(ec) == NBSL_PP_OBS)
return;
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