From: nadav.amit@gmail.com
To: Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com,
Thomas Gleixner <tglx@linutronix.de>,
Nadav Amit <nadav.amit@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
linux_dti@icloud.com, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org, akpm@linux-foundation.org,
kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
will.deacon@arm.com, ard.biesheuvel@linaro.org,
kristen@linux.intel.com, deneen.t.dock@intel.com,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Nadav Amit <namit@vmware.com>,
Masami Hiramatsu <mhiramat@kernel.org>
Subject: [PATCH v6 22/24] x86/alternative: Comment about module removal races
Date: Fri, 26 Apr 2019 16:23:01 -0700 [thread overview]
Message-ID: <20190426232303.28381-23-nadav.amit@gmail.com> (raw)
In-Reply-To: <20190426232303.28381-1-nadav.amit@gmail.com>
From: Nadav Amit <namit@vmware.com>
Add a comment to clarify that users of text_poke() must ensure that
no races with module removal take place.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
arch/x86/kernel/alternative.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 18f959975ea0..7b9b49dfc05a 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -810,6 +810,11 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
* It means the size must be writable atomically and the address must be aligned
* in a way that permits an atomic write. It also makes sure we fit on a single
* page.
+ *
+ * Note that the caller must ensure that if the modified code is part of a
+ * module, the module would not be removed during poking. This can be achieved
+ * by registering a module notifier, and ordering module removal and patching
+ * trough a mutex.
*/
void *text_poke(void *addr, const void *opcode, size_t len)
{
--
2.17.1
next prev parent reply other threads:[~2019-04-26 23:23 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 23:22 [PATCH v6 00/24] x86: text_poke() fixes and executable lockdowns nadav.amit
2019-04-26 23:22 ` [PATCH v6 01/24] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" nadav.amit
2019-04-26 23:22 ` [PATCH v6 02/24] x86/jump_label: Use text_poke_early() during early init nadav.amit
2019-04-26 23:22 ` [PATCH v6 03/24] x86/mm: Introduce temporary mm structs nadav.amit
2019-04-26 23:22 ` [PATCH v6 04/24] x86/mm: Save debug registers when loading a temporary mm nadav.amit
2019-04-26 23:22 ` [PATCH v6 05/24] uprobes: Initialize uprobes earlier nadav.amit
2019-04-26 23:22 ` [PATCH v6 06/24] fork: Provide a function for copying init_mm nadav.amit
2019-04-26 23:22 ` [PATCH v6 07/24] x86/alternative: Initialize temporary mm for patching nadav.amit
2019-04-26 23:22 ` [PATCH v6 08/24] x86/alternative: Use temporary mm for text poking nadav.amit
2019-04-26 23:22 ` [PATCH v6 09/24] x86/kgdb: Avoid redundant comparison of patched code nadav.amit
2019-04-26 23:22 ` [PATCH v6 10/24] x86/ftrace: Set trampoline pages as executable nadav.amit
2019-04-26 23:22 ` [PATCH v6 11/24] x86/kprobes: Set instruction page " nadav.amit
2019-04-26 23:22 ` [PATCH v6 12/24] x86/module: Avoid breaking W^X while loading modules nadav.amit
2019-04-26 23:22 ` [PATCH v6 13/24] x86/jump-label: Remove support for custom poker nadav.amit
2019-04-26 23:22 ` [PATCH v6 14/24] x86/alternative: Remove the return value of text_poke_*() nadav.amit
2019-04-26 23:22 ` [PATCH v6 15/24] x86/mm/cpa: Add set_direct_map_ functions nadav.amit
2019-04-26 23:22 ` [PATCH v6 16/24] mm: Make hibernate handle unmapped pages nadav.amit
2019-04-26 23:22 ` [PATCH v6 17/24] vmalloc: Add flag for free of special permsissions nadav.amit
2019-04-26 23:22 ` [PATCH v6 18/24] modules: Use vmalloc special flag nadav.amit
2019-04-26 23:22 ` [PATCH v6 19/24] bpf: " nadav.amit
2019-04-26 23:22 ` [PATCH v6 20/24] x86/ftrace: " nadav.amit
2019-04-26 23:23 ` [PATCH v6 21/24] x86/kprobes: " nadav.amit
2019-04-26 23:23 ` nadav.amit [this message]
2019-04-26 23:23 ` [PATCH v6 23/24] mm/tlb: Provide default nmi_uaccess_okay() nadav.amit
2019-04-26 23:23 ` [PATCH v6 24/24] bpf: Fail bpf_probe_write_user() while mm is switched nadav.amit
2019-04-27 10:22 ` [PATCH v6 00/24] x86: text_poke() fixes and executable lockdowns Ingo Molnar
2019-04-27 10:32 ` Peter Zijlstra
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