[PATCH 5.18 037/879] x86/MCE/AMD: Fix memory leak when threshold_create_bank() fails

Greg Kroah-Hartman
2022-06-07T21:57:00Z

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

commit e5f28623ceb103e13fc3d7bd45edf9818b227fd0 upstream.

In mce_threshold_create_device(), if threshold_create_bank() fails, the
previously allocated threshold banks array @bp will be leaked because
the call to mce_threshold_remove_device() will not free it.

This happens because mce_threshold_remove_device() fetches the pointer
through the threshold_banks per-CPU variable but bp is written there
only after the bank creation is successful, and not before, when
threshold_create_bank() fails.

Add a helper which unwinds all the bank creation work previously done
and pass into it the previously allocated threshold banks array for
freeing.

[ bp: Massage. ]

Fixes: 6458de97fc15 ("x86/mce/amd: Straighten CPU hotplug path")
Co-developed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>
Signed-off-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>
Co-developed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220329104705.65256-3-ammarfaizi2@gnuweeb.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kernel/cpu/mce/amd.c | 32 +++++++++++++++++++-------------
1 file changed, 19 insertions(+), 13 deletions(-)

--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -1294,10 +1294,23 @@ out_free:
kfree(bank);
}

+static void __threshold_remove_device(struct threshold_bank **bp)
+{
+ unsigned int bank, numbanks = this_cpu_read(mce_num_banks);
+
+ for (bank = 0; bank < numbanks; bank++) {
+ if (!bp[bank])
+ continue;
+
+ threshold_remove_bank(bp[bank]);
+ bp[bank] = NULL;
+ }
+ kfree(bp);
+}
+
int mce_threshold_remove_device(unsigned int cpu)
{
struct threshold_bank **bp = this_cpu_read(threshold_banks);
- unsigned int bank, numbanks = this_cpu_read(mce_num_banks);

if (!bp)
return 0;
@@ -1308,13 +1321,7 @@ int mce_threshold_remove_device(unsigned
*/
this_cpu_write(threshold_banks, NULL);

- for (bank = 0; bank < numbanks; bank++) {
- if (bp[bank]) {
- threshold_remove_bank(bp[bank]);
- bp[bank] = NULL;
- }
- }
- kfree(bp);
+ __threshold_remove_device(bp);
return 0;
}

@@ -1351,15 +1358,14 @@ int mce_threshold_create_device(unsigned
if (!(this_cpu_read(bank_map) & (1 << bank)))
continue;
err = threshold_create_bank(bp, cpu, bank);
- if (err)
- goto out_err;
+ if (err) {
+ __threshold_remove_device(bp);
+ return err;
+ }
}
this_cpu_write(threshold_banks, bp);

if (thresholding_irq_en)
mce_threshold_vector = amd_threshold_interrupt;
return 0;
-out_err:
- mce_threshold_remove_device(cpu);
- return err;
}