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| author | Jeff Dike <jdike@addtoit.com> | 2007-05-23 13:57:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-23 20:14:12 -0700 |
| commit | cf6acedbeac17dea1c1eed85048a72e188f3f768 (patch) | |
| tree | d5c1b4e5b9a5e8c22198bc92839c80305641cb09 /arch | |
| parent | da90fa8ff671a0139772ec3b3e82c06077e82122 (diff) | |
| download | linux-stable-cf6acedbeac17dea1c1eed85048a72e188f3f768.tar.gz linux-stable-cf6acedbeac17dea1c1eed85048a72e188f3f768.tar.bz2 linux-stable-cf6acedbeac17dea1c1eed85048a72e188f3f768.zip | |
uml: improve PTRACE_SYSEMU checking
Make the PTRACE_SYSEMU checking more robust. It will make sure that system
call numbers are reported correctly. If there is a problem, it will disable
PTRACE_SYSEMU use and use PTRACE_SYSCALL instead.
Thanks to Balaji G for helping reproduce this problem.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/um/os-Linux/start_up.c | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index 79471f85eb89..3fc13fa8729d 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -144,9 +144,7 @@ static int stop_ptraced_child(int pid, void *stack, int exitcode, int exit_with = WEXITSTATUS(status); if (exit_with == 2) non_fatal("check_ptrace : child exited with status 2. " - "Serious trouble happening! Try updating " - "your host skas patch!\nDisabling SYSEMU " - "support."); + "\nDisabling SYSEMU support.\n"); non_fatal("check_ptrace : child exited with exitcode %d, while " "expecting %d; status 0x%x\n", exit_with, exitcode, status); @@ -209,6 +207,7 @@ __uml_setup("nosysemu", nosysemu_cmd_param, static void __init check_sysemu(void) { void *stack; + unsigned long regs[MAX_REG_NR]; int pid, n, status, count=0; non_fatal("Checking syscall emulation patch for ptrace..."); @@ -225,11 +224,20 @@ static void __init check_sysemu(void) fatal("check_sysemu : expected SIGTRAP, got status = %d", status); - n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, - os_getpid()); - if(n < 0) - fatal_perror("check_sysemu : failed to modify system call " - "return"); + if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0) + fatal_perror("check_sysemu : PTRACE_GETREGS failed"); + if(PT_SYSCALL_NR(regs) != __NR_getpid){ + non_fatal("check_sysemu got system call number %d, " + "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid); + goto fail; + } + + n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid()); + if(n < 0){ + non_fatal("check_sysemu : failed to modify system call " + "return"); + goto fail; + } if (stop_ptraced_child(pid, stack, 0, 0) < 0) goto fail_stopped; |