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@@ -1,80 +0,0 @@
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-From 613e601bb4b50dc359b41f162a5b629449e4bbea Mon Sep 17 00:00:00 2001
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-From: Carlos Santos <casantos@redhat.com>
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-Date: Fri, 18 Oct 2019 22:02:49 -0300
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-Subject: [PATCH] Circumvent bug in uClibc-ng syscall() on x86_64 systems
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-
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-On uClibc at least up to v1.0.32, syscall() for x86_64 is defined in
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-libc/sysdeps/linux/x86_64/syscall.S as
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-
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-syscall:
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- movq %rdi, %rax /* Syscall number -> rax. */
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- movq %rsi, %rdi /* shift arg1 - arg5. */
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- movq %rdx, %rsi
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- movq %rcx, %rdx
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- movq %r8, %r10
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- movq %r9, %r8
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- movq 8(%rsp),%r9 /* arg6 is on the stack. */
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- syscall /* Do the system call. */
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- cmpq $-4095, %rax /* Check %rax for error. */
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- jae __syscall_error /* Branch forward if it failed. */
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- ret /* Return to caller. */
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-
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-And __syscall_error is defined in
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-libc/sysdeps/linux/x86_64/__syscall_error.c as
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-
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-int __syscall_error(void) attribute_hidden;
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-int __syscall_error(void)
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-{
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- register int err_no __asm__ ("%rcx");
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- __asm__ ("mov %rax, %rcx\n\t"
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- "neg %rcx");
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- __set_errno(err_no);
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- return -1;
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-}
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-
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-Notice that __syscall_error returns -1 as a 32-bit int in %rax, a 64-bit
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-register i.e. 0x00000000ffffffff (decimal 4294967295). When this value
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-is compared to -1 in _sys_chk_seccomp_flag_kernel() the result is false,
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-leading the function to always return 0.
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-
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-Prevent the error by coercing the return value of syscall() to int in a
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-temporary variable before comparing it to -1. We could use just an (int)
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-cast but the variable makes the code more readable and the machine code
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-generated by the compiler is the same in both cases.
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-
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-All other syscall() invocations were inspected and they either already
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-coerce the result to int or do not compare it to -1.
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-
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-The same problem probably occurs on other 64-bit systems but so far only
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-x86_64 was tested.
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-
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-A bug report is being submitted to uClibc.
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-
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-Signed-off-by: Carlos Santos <casantos@redhat.com>
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----
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- src/system.c | 8 +++++---
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- 1 file changed, 5 insertions(+), 3 deletions(-)
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-
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-diff --git a/src/system.c b/src/system.c
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-index 8e5aafc..811b401 100644
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---- a/src/system.c
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-+++ b/src/system.c
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-@@ -215,10 +215,12 @@ static int _sys_chk_seccomp_flag_kernel(int flag)
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- /* this is an invalid seccomp(2) call because the last argument
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- * is NULL, but depending on the errno value of EFAULT we can
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- * guess if the filter flag is supported or not */
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-- if (sys_chk_seccomp_syscall() == 1 &&
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-- syscall(_nr_seccomp, SECCOMP_SET_MODE_FILTER, flag, NULL) == -1 &&
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-- errno == EFAULT)
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-+ int rc;
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-+ if (sys_chk_seccomp_syscall() == 1) {
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-+ rc = syscall(_nr_seccomp, SECCOMP_SET_MODE_FILTER, flag, NULL);
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-+ if (rc == -1 && errno == EFAULT)
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- return 1;
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-+ }
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-
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- return 0;
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- }
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---
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-2.18.1
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-
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Peter Korsgaard