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

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

[Borislav Petkov]

From: "Borislav Petkov (AMD)" <bp@alien8.de>

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) <bp@alien8.de>
Cc: <stable@kernel.org>
---
 drivers/edac/edac_mc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 07d3f73bcd23..fd70caa85574 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -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;
-- 
2.51.0

RE: [PATCH] EDAC/mc: Fix error path ordering in edac_mc_alloc()

[Zhuo, Qiuxu]

> From: Borislav Petkov <bp@kernel.org>
> [...]
> Subject: [PATCH] EDAC/mc: Fix error path ordering in edac_mc_alloc()
> 
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
> 
> 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) <bp@alien8.de>
> Cc: <stable@kernel.org>

LGTM. Thanks.

  Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>

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