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EDAC/mc: Fix error path ordering in edac_mc_alloc()

PATCH In review Borislav Petkov 2 participants 2 messages Mar 31 – Apr 1 EDAC-core

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Borislav Petkov

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PATCH 1/1 EDAC/mc: Fix error path ordering in edac_mc_alloc()

From: "Borislav Petkov (AMD)" <[email protected]>

When the mci->pvt_info allocation in edac_mc_alloc() fails, the error path will call put_device() which will end up calling the device's release function.

However, the init ordering is wrong such that device_initialize() happens *after* the failed allocation and thus the device itself and the release function pointer are not initialized yet when they're called:

MCE: In-kernel MCE decoding enabled.

  ------------[ cut here ]------------
  kobject: '(null)': is not initialized, yet kobject_put() is being called.
  WARNING: lib/kobject.c:734 at kobject_put, CPU#22: systemd-udevd
  CPU: 22 UID: 0 PID: 538 Comm: systemd-udevd Not tainted 7.0.0-rc1+ #2 PREEMPT(full)
  RIP: 0010:kobject_put
  Call Trace:
   <TASK>
   edac_mc_alloc+0xbe/0xe0 [edac_core]
   amd64_edac_init+0x7a4/0xff0 [amd64_edac]
   ? __pfx_amd64_edac_init+0x10/0x10 [amd64_edac]
   do_one_initcall
   ...

Reorder the calling sequence such that the device is initialized and thus the release function pointer is properly set before it can be used.

This was found by Claude while reviewing another EDAC patch.

Fixes 0bbb265f7089 ("EDAC/mc: Get rid of silly one-shot struct allocation in edac_mc_alloc()")
Reported-by Claude Code:claude-opus-4.5
Signed-off-by Borislav Petkov (AMD) <[email protected]>
Cc <[email protected]>
---
 drivers/edac/edac_mc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
drivers/edac/edac_mc.c +3 -3
index 07d3f73bcd23..fd70caa85574 100644
@@ -367,13 +367,13 @@ struct mem_ctl_info *edac_mc_alloc(unsigned int mc_num,
 	mci->n_layers = n_layers;
 	memcpy(mci->layers, layers, sizeof(*layer) * n_layers);
 
+	mci->dev.release = mci_release;
+	device_initialize(&mci->dev);
+
 	mci->pvt_info = kzalloc(sz_pvt, GFP_KERNEL);
 	if (!mci->pvt_info)
 		goto error;
 
-	mci->dev.release = mci_release;
-	device_initialize(&mci->dev);
-
 	/* setup index and various internal pointers */
 	mci->mc_idx = mc_num;
 	mci->tot_dimms = tot_dimms;
Signature · 1 line
2.51.0
Reviewed-by on v1 1/1
#1 lore raw
Quoted 32 lines

From: Borislav Petkov <[email protected]>
[...]
Subject: [PATCH] EDAC/mc: Fix error path ordering in edac_mc_alloc()

From: "Borislav Petkov (AMD)" <[email protected]>

When the mci->pvt_info allocation in edac_mc_alloc() fails, the error path will call put_device() which will end up calling the device's release function.

However, the init ordering is wrong such that device_initialize() happens *after* the failed allocation and thus the device itself and the release function pointer are not initialized yet when they're called:

MCE: In-kernel MCE decoding enabled.

  ------------[ cut here ]------------
  kobject: '(null)': is not initialized, yet kobject_put() is being called.
  WARNING: lib/kobject.c:734 at kobject_put, CPU#22: systemd-udevd
  CPU: 22 UID: 0 PID: 538 Comm: systemd-udevd Not tainted 7.0.0-rc1+ #2
PREEMPT(full)
  RIP: 0010:kobject_put
  Call Trace:
   <TASK>
   edac_mc_alloc+0xbe/0xe0 [edac_core]
   amd64_edac_init+0x7a4/0xff0 [amd64_edac]
   ? __pfx_amd64_edac_init+0x10/0x10 [amd64_edac]
   do_one_initcall
   ...

Reorder the calling sequence such that the device is initialized and thus the release function pointer is properly set before it can be used.

Quoted 7 lines

This was found by Claude while reviewing another EDAC patch.

Fixes 0bbb265f7089 ("EDAC/mc: Get rid of silly one-shot struct allocation in

edac_mc_alloc()")

Reported-by Claude Code:claude-opus-4.5
Signed-off-by Borislav Petkov (AMD) <[email protected]>
Cc <[email protected]>

LGTM. Thanks.

Reviewed-by Qiuxu Zhuo <[email protected]>

[...]