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From: Amanieu d'Antras <amanieu@gmail.com>
Cc: Amanieu d'Antras <amanieu@gmail.com>,
	Ryan Houdek <Houdek.Ryan@fex-emu.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Steven Price <steven.price@arm.com>,
	Arnd Bergmann <arnd@kernel.org>,
	David Laight <David.Laight@aculab.com>,
	Mark Brown <broonie@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 7/8] arm64: Forbid calling compat sigreturn from 64-bit tasks
Date: Fri, 30 Apr 2021 21:37:56 +0100	[thread overview]
Message-ID: <20210430203757.47653-6-amanieu@gmail.com> (raw)
In-Reply-To: <20210430202810.44092-1-amanieu@gmail.com>

It's impossible for this syscall to do anything sensible in this
context.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Co-developed-by: Ryan Houdek <Houdek.Ryan@fex-emu.org>
Signed-off-by: Ryan Houdek <Houdek.Ryan@fex-emu.org>
---
 arch/arm64/kernel/signal32.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 2f507f565c48..e2bdd1eaefd8 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -237,6 +237,10 @@ COMPAT_SYSCALL_DEFINE0(sigreturn)
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
 
+	/* Reject attempts to call this from a 64-bit process. */
+	if (!is_compat_task())
+		goto badframe;
+
 	/*
 	 * Since we stacked the signal on a 64-bit boundary,
 	 * then 'sp' should be word aligned here.  If it's
@@ -268,6 +272,10 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
 
+	/* Reject attempts to call this from a 64-bit process. */
+	if (!is_compat_task())
+		goto badframe;
+
 	/*
 	 * Since we stacked the signal on a 64-bit boundary,
 	 * then 'sp' should be word aligned here.  If it's
-- 
2.31.1


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  parent reply	other threads:[~2021-04-30 20:42 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-30 20:28 [PATCH v4 0/8] arm64: Allow 64-bit tasks to invoke compat syscalls Amanieu d'Antras
2021-04-30 20:28 ` [PATCH v4 1/8] mm: Add arch_get_mmap_base_topdown macro Amanieu d'Antras
2021-04-30 20:37 ` [PATCH v4 2/8] hugetlbfs: Use arch_get_mmap_* macros Amanieu d'Antras
2021-04-30 20:37 ` [PATCH v4 3/8] mm: Support mmap_compat_base with the generic layout Amanieu d'Antras
2021-04-30 20:37 ` [PATCH v4 4/8] arm64: Separate in_compat_syscall from is_compat_task Amanieu d'Antras
2021-04-30 20:37 ` [PATCH v4 5/8] arm64: mm: Use HAVE_ARCH_COMPAT_MMAP_BASES Amanieu d'Antras
2021-04-30 20:37 ` [PATCH v4 6/8] arm64: Add a compat syscall flag to thread_info Amanieu d'Antras
2021-04-30 20:37 ` Amanieu d'Antras [this message]
2021-04-30 20:37 ` [PATCH v4 8/8] arm64: Allow 64-bit tasks to invoke compat syscalls Amanieu d'Antras

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