Semantics of the microcode reload file are only defined if a "1" is
written. But the code silently treats any other unsigned integer as a
successful write even though no actions are performed to load microcode.
Report those erroneous writes back to user.
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ashok Raj <[email protected]>
Cc: LKML <[email protected]>
Cc: x86 <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Alison Schofield <[email protected]>
Cc: Reinette Chatre <[email protected]>
Cc: Thomas Gleixner (Intel) <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Stefan Talpalaru <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Peter Zilstra (Intel) <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andrew Cooper <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Martin Pohlack <[email protected]>
---
arch/x86/kernel/cpu/microcode/core.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 1c6831b8b244..e4b4dfcf2d18 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -476,11 +476,8 @@ static ssize_t reload_store(struct device *dev,
ssize_t ret;
ret = kstrtoul(buf, 0, &val);
- if (ret)
- return ret;
-
- if (val != 1)
- return size;
+ if (ret || val != 1)
+ return -EINVAL;
cpus_read_lock();
--
2.37.2
The following commit has been merged into the x86/microcode branch of tip:
Commit-ID: 25d0dc4b957cc8674f8554e85f18a00467e876d7
Gitweb: https://git.kernel.org/tip/25d0dc4b957cc8674f8554e85f18a00467e876d7
Author: Ashok Raj <[email protected]>
AuthorDate: Mon, 30 Jan 2023 13:39:48 -08:00
Committer: Borislav Petkov (AMD) <[email protected]>
CommitterDate: Tue, 31 Jan 2023 16:47:03 +01:00
x86/microcode: Allow only "1" as a late reload trigger value
Microcode gets reloaded late only if "1" is written to the reload file.
However, the code silently treats any other unsigned integer as a
successful write even though no actions are performed to load microcode.
Make the loader more strict to accept only "1" as a trigger value and
return an error otherwise.
[ bp: Massage commit message. ]
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ashok Raj <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/kernel/cpu/microcode/core.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 61d57d9..fdd1e7e 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -475,11 +475,8 @@ static ssize_t reload_store(struct device *dev,
ssize_t ret = 0;
ret = kstrtoul(buf, 0, &val);
- if (ret)
- return ret;
-
- if (val != 1)
- return size;
+ if (ret || val != 1)
+ return -EINVAL;
cpus_read_lock();