From: Borislav Petkov bp@suse.de
[ Upstream commit 6d8e294bf5f0e85c34e8b14b064e2965f53f38b0 ]
When inserting random PFNs for debugging the CEC through (debugfs)/ras/cec/pfn, depending on the return value of pfn_set(), multiple values get inserted per a single write.
That is because simple_attr_write() interprets a retval of 0 as success and claims the whole input. However, pfn_set() returns the cec_add_elem() value, which, if > 0 and smaller than the whole input length, makes glibc continue issuing the write syscall until there's input left:
pfn_set simple_attr_write debugfs_attr_write full_proxy_write vfs_write ksys_write do_syscall_64 entry_SYSCALL_64_after_hwframe
leading to those repeated calls.
Return 0 to fix that.
Signed-off-by: Borislav Petkov bp@suse.de Cc: Tony Luck tony.luck@intel.com Cc: linux-edac linux-edac@vger.kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/ras/cec.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c index f85d6b7a1984..5d2b2c02cbbe 100644 --- a/drivers/ras/cec.c +++ b/drivers/ras/cec.c @@ -369,7 +369,9 @@ static int pfn_set(void *data, u64 val) { *(u64 *)data = val;
- return cec_add_elem(val); + cec_add_elem(val); + + return 0; }
DEFINE_DEBUGFS_ATTRIBUTE(pfn_ops, u64_get, pfn_set, "0x%llx\n");