Linux-RISC-V Archive on lore.kernel.org
 help / color / Atom feed
From: David Abdurachmanov <david.abdurachmanov@gmail.com>
To: palmer@sifive.com, aou@eecs.berkeley.edu, keescook@chromium.org,
	luto@amacapital.net, wad@chromium.org, green.hu@gmail.com,
	deanbo422@gmail.com, linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org
Cc: David Abdurachmanov <david.abdurachmanov@gmail.com>
Subject: [PATCH 2/2] riscv: fix syscall_{get,set}_arguments
Date: Thu,  6 Dec 2018 16:01:56 +0100
Message-ID: <20181206150156.28210-3-david.abdurachmanov@gmail.com> (raw)
In-Reply-To: <20181206150156.28210-1-david.abdurachmanov@gmail.com>

Testing with libseccomp master branch revealed that testcases with
filters on syscall arguments were failing due to wrong values. Seccomp
uses syscall_get_argumentsi() to copy syscall arguments, and there is a
bug in pointer arithmetics in memcpy() call.

Two alternative implementation were tested: the one in this patch and
another one based on while-break loop. Both delivered the same results.

This implementation is also used in arm, arm64 and nds32 arches.

Signed-off-by: David Abdurachmanov <david.abdurachmanov@gmail.com>
---
 arch/riscv/include/asm/syscall.h | 42 ++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
index bba3da6ef157..26ceb434a433 100644
--- a/arch/riscv/include/asm/syscall.h
+++ b/arch/riscv/include/asm/syscall.h
@@ -70,19 +70,32 @@ static inline void syscall_set_return_value(struct task_struct *task,
 	regs->a0 = (long) error ?: val;
 }
 
+#define SYSCALL_MAX_ARGS 6
+
 static inline void syscall_get_arguments(struct task_struct *task,
 					 struct pt_regs *regs,
 					 unsigned int i, unsigned int n,
 					 unsigned long *args)
 {
-	BUG_ON(i + n > 6);
+	if (n == 0)
+		return;
+
+	if (i + n > SYSCALL_MAX_ARGS) {
+		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
+		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
+		pr_warning("%s called with max args %d, handling only %d\n",
+			__func__, i + n, SYSCALL_MAX_ARGS);
+		memset(args_bad, 0, n_bad * sizeof(args[0]));
+	}
+
 	if (i == 0) {
 		args[0] = regs->orig_a0;
 		args++;
 		i++;
 		n--;
 	}
-	memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
+
+	memcpy(args, &regs->a0 + i, n * sizeof(args[0]));
 }
 
 static inline void syscall_set_arguments(struct task_struct *task,
@@ -90,14 +103,23 @@ static inline void syscall_set_arguments(struct task_struct *task,
 					 unsigned int i, unsigned int n,
 					 const unsigned long *args)
 {
-	BUG_ON(i + n > 6);
-        if (i == 0) {
-                regs->orig_a0 = args[0];
-                args++;
-                i++;
-                n--;
-        }
-	memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
+	if (n == 0)
+		return;
+
+	if (i + n > SYSCALL_MAX_ARGS) {
+		pr_warning("%s called with max args %d, handling only %d\n",
+			__func__, i + n, SYSCALL_MAX_ARGS);
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		regs->orig_a0 = args[0];
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(&regs->a0 + i, args, n * sizeof(args[0]));
 }
 
 static inline int syscall_get_arch(void)
-- 
2.19.2


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-06 15:01 [PATCH 0/2] riscv: add support for SECCOMP and SECCOMP_FILTER David Abdurachmanov
2018-12-06 15:01 ` [PATCH 1/2] riscv: add support for SECCOMP incl. filters David Abdurachmanov
2018-12-06 16:47   ` Kees Cook
2018-12-06 17:10     ` David Abdurachmanov
2018-12-06 16:51   ` Kees Cook
2018-12-06 17:11     ` David Abdurachmanov
2018-12-06 18:25     ` David Abdurachmanov
2018-12-06 18:32       ` Kees Cook
2018-12-06 17:06   ` Kees Cook
2018-12-06 17:12     ` David Abdurachmanov
2018-12-06 15:01 ` David Abdurachmanov [this message]
2018-12-06 16:48   ` [PATCH 2/2] riscv: fix syscall_{get,set}_arguments Kees Cook
2018-12-06 17:13     ` David Abdurachmanov

Reply instructions:

You may reply publically 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=20181206150156.28210-3-david.abdurachmanov@gmail.com \
    --to=david.abdurachmanov@gmail.com \
    --cc=aou@eecs.berkeley.edu \
    --cc=deanbo422@gmail.com \
    --cc=green.hu@gmail.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=luto@amacapital.net \
    --cc=palmer@sifive.com \
    --cc=wad@chromium.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

Linux-RISC-V Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-riscv/0 linux-riscv/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-riscv linux-riscv/ https://lore.kernel.org/linux-riscv \
		linux-riscv@lists.infradead.org infradead-linux-riscv@archiver.kernel.org
	public-inbox-index linux-riscv


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-riscv


AGPL code for this site: git clone https://public-inbox.org/ public-inbox