From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v7 5/9] x86/microcode/AMD: Split status from data to skip in verify_and_add_patch()
Date: Tue, 19 Jun 2018 20:47:35 +0200 [thread overview]
Message-ID: <84b3976f5879d7a58c3774d1f86e493b34c9759c.1529424596.git.mail@maciej.szmigiero.name> (raw)
In-Reply-To: <cover.1529424596.git.mail@maciej.szmigiero.name>
verify_and_add_patch() returned a single "int" value which encoded both
this function error status and also a length of microcode container data to
skip.
Unfortunately, ranges of these two values collide: the length of data to
skip can be any value between 1 and UINT_MAX, so, for example, error status
of -EINVAL maps to a valid return value of 4294967274 bytes.
That's why these two values need to be split.
Let's keep the common convention that a function zero return value means
success while a negative value means an error while moving the returned
length of microcode container data to skip to a separate output parameter.
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
---
arch/x86/kernel/cpu/microcode/amd.c | 35 +++++++++++++++--------------
1 file changed, 18 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index c05531540b57..9e29374ce4d0 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -754,45 +754,46 @@ static void cleanup(void)
}
/*
- * We return the current size even if some of the checks failed so that
- * we can skip over the next patch. If we return a negative value, we
- * signal a grave error like a memory allocation has failed and the
- * driver cannot continue functioning normally. In such cases, we tear
- * down everything we've used up so far and exit.
+ * We return zero (success) and the current patch data size in @crnt_size
+ * even if some of the checks failed so that we can skip over the next patch.
+ * If we return a negative value, we signal a grave error like a memory
+ * allocation has failed and the driver cannot continue functioning normally.
+ * In such cases, we tear down everything we've used up so far and exit.
*/
-static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover)
+static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover,
+ unsigned int *crnt_size)
{
struct microcode_header_amd *mc_hdr;
struct ucode_patch *patch;
- unsigned int patch_size, crnt_size;
+ unsigned int patch_size;
u32 proc_fam;
u16 proc_id;
patch_size = *(u32 *)(fw + 4);
- crnt_size = patch_size + SECTION_HDR_SIZE;
+ *crnt_size = patch_size + SECTION_HDR_SIZE;
mc_hdr = (struct microcode_header_amd *)(fw + SECTION_HDR_SIZE);
proc_id = mc_hdr->processor_rev_id;
proc_fam = find_cpu_family_by_equiv_cpu(proc_id);
if (!proc_fam) {
pr_err("No patch family for equiv ID: 0x%04x\n", proc_id);
- return crnt_size;
+ return 0;
}
/* check if patch is for the current family */
proc_fam = ((proc_fam >> 8) & 0xf) + ((proc_fam >> 20) & 0xff);
if (proc_fam != family)
- return crnt_size;
+ return 0;
if (mc_hdr->nb_dev_id || mc_hdr->sb_dev_id) {
pr_err("Patch-ID 0x%08x: chipset-specific code unsupported.\n",
mc_hdr->patch_id);
- return crnt_size;
+ return 0;
}
- if (!verify_patch(family, fw, leftover, &crnt_size, false)) {
+ if (!verify_patch(family, fw, leftover, crnt_size, false)) {
pr_err("Patch-ID 0x%08x: size mismatch.\n", mc_hdr->patch_id);
- return crnt_size;
+ return 0;
}
patch = kzalloc(sizeof(*patch), GFP_KERNEL);
@@ -818,7 +819,7 @@ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover)
/* ... and add to cache. */
update_cache(patch);
- return crnt_size;
+ return 0;
}
static enum ucode_state __load_microcode_amd(u8 family, const u8 *data,
@@ -827,7 +828,6 @@ static enum ucode_state __load_microcode_amd(u8 family, const u8 *data,
enum ucode_state ret = UCODE_ERROR;
unsigned int leftover;
u8 *fw = (u8 *)data;
- int crnt_size = 0;
int offset;
offset = install_equiv_cpu_table(data);
@@ -845,8 +845,9 @@ static enum ucode_state __load_microcode_amd(u8 family, const u8 *data,
}
while (leftover) {
- crnt_size = verify_and_add_patch(family, fw, leftover);
- if (crnt_size < 0)
+ unsigned int crnt_size;
+
+ if (verify_and_add_patch(family, fw, leftover, &crnt_size) < 0)
return ret;
fw += crnt_size;
next prev parent reply other threads:[~2018-06-19 18:47 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-19 18:47 [PATCH v7 0/9] x86/microcode/AMD: Check microcode file sanity before loading it Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 1/9] x86/microcode/AMD: Subtract SECTION_HDR_SIZE from file leftover length Maciej S. Szmigiero
2018-11-19 10:12 ` [tip:x86/microcode] " tip-bot for Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 2/9] x86/microcode/AMD: Add microcode container data checking functions Maciej S. Szmigiero
2018-11-19 10:13 ` [tip:x86/microcode] x86/microcode/AMD: Add microcode container verification tip-bot for Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 3/9] x86/microcode/AMD: Integrate verify_patch_size() into verify_patch() Maciej S. Szmigiero
2018-06-21 8:36 ` Borislav Petkov
2018-06-22 22:32 ` [PATCH 1/2] " Maciej S. Szmigiero
2018-06-22 22:33 ` [PATCH 2/2] x86/microcode/AMD: Check patch size for all known CPU families Maciej S. Szmigiero
2018-06-25 18:37 ` Borislav Petkov
2018-06-25 22:18 ` Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 4/9] x86/microcode/AMD: Check microcode container data in the early loader Maciej S. Szmigiero
2018-06-19 18:47 ` Maciej S. Szmigiero [this message]
2018-06-19 18:47 ` [PATCH v7 6/9] x86/microcode/AMD: Check microcode container data in the late loader Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 7/9] x86/microcode/AMD: Add a reminder about PATCH_MAX_SIZE macro Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 8/9] x86/microcode/AMD: Convert CPU equivalence table variable into a struct Maciej S. Szmigiero
2018-06-19 18:47 ` [PATCH v7 9/9] x86/microcode/AMD: Check the equivalence table size when scanning it Maciej S. Szmigiero
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=84b3976f5879d7a58c3774d1f86e493b34c9759c.1529424596.git.mail@maciej.szmigiero.name \
--to=mail@maciej.szmigiero.name \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).