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x86/mce/amd: Publish the bank pointer only after setup has succeeded 

threshold_create_bank() creates a bank descriptor per MCA error
thresholding counter which can be controlled over sysfs. It publishes
the pointer to that bank in a per-CPU variable and then goes on to
create additional thresholding blocks if the bank has such.

However, that creation of additional blocks in
allocate_threshold_blocks() can fail, leading to a use-after-free
through the per-CPU pointer.

Therefore, publish that pointer only after all blocks have been setup
successfully.

Fixes: 019f34fccf ("x86, MCE, AMD: Move shared bank to node descriptor")
Reported-by: Saar Amar <Saar.Amar@microsoft.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200128140846.phctkvx5btiexvbx@kili.mountain
This commit is contained in:
Borislav Petkov 2020-02-04 13:28:41 +01:00
parent bb6d3fb354
commit 6e5cf31fbe
1 changed files with 16 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
arch/x86/kernel/cpu/mce/amd.c
View File

@ -1198,8 +1198,9 @@ static const char *get_name(unsigned int bank, struct threshold_block *b)
return buf_mcatype;
}
static int allocate_threshold_blocks(unsigned int cpu, unsigned int bank,
unsigned int block, u32 address)
static int allocate_threshold_blocks(unsigned int cpu, struct threshold_bank *tb,
unsigned int bank, unsigned int block,
u32 address)
{
struct threshold_block *b = NULL;
u32 low, high;
@ -1243,16 +1244,12 @@ static int allocate_threshold_blocks(unsigned int cpu, unsigned int bank,
INIT_LIST_HEAD(&b->miscj);
if (per_cpu(threshold_banks, cpu)[bank]->blocks) {
list_add(&b->miscj,
&per_cpu(threshold_banks, cpu)[bank]->blocks->miscj);
} else {
per_cpu(threshold_banks, cpu)[bank]->blocks = b;
}
if (tb->blocks)
list_add(&b->miscj, &tb->blocks->miscj);
else
tb->blocks = b;
err = kobject_init_and_add(&b->kobj, &threshold_ktype,
per_cpu(threshold_banks, cpu)[bank]->kobj,
get_name(bank, b));
err = kobject_init_and_add(&b->kobj, &threshold_ktype, tb->kobj, get_name(bank, b));
if (err)
goto out_free;
recurse:
@ -1260,7 +1257,7 @@ recurse:
if (!address)
return 0;
err = allocate_threshold_blocks(cpu, bank, block, address);
err = allocate_threshold_blocks(cpu, tb, bank, block, address);
if (err)
goto out_free;
@ -1345,8 +1342,6 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank)
goto out_free;
}
per_cpu(threshold_banks, cpu)[bank] = b;
if (is_shared_bank(bank)) {
refcount_set(&b->cpus, 1);
@ -1357,9 +1352,13 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank)
}
}
err = allocate_threshold_blocks(cpu, bank, 0, msr_ops.misc(bank));
if (!err)
goto out;
err = allocate_threshold_blocks(cpu, b, bank, 0, msr_ops.misc(bank));
if (err)
goto out_free;
per_cpu(threshold_banks, cpu)[bank] = b;
return 0;
out_free:
kfree(b);