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| author | Jeff Dike <jdike@addtoit.com> | 2007-03-23 15:37:30 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-04-06 03:43:11 -0700 |
| commit | 6f6017090339ddb751b3c71840c214282214f6bc (patch) | |
| tree | 85292a6a7251d8689b8378ffeb134736243f51ef /arch | |
| parent | edfcf73f3005c29f7f28f4fcd47cfbfc06af10bb (diff) | |
| download | lwn-6f6017090339ddb751b3c71840c214282214f6bc.tar.gz lwn-6f6017090339ddb751b3c71840c214282214f6bc.zip | |
UML - host VDSO fix
This fixes a problem seen by a number of people running UML on newer host
kernels. init would hang with an infinite segfault loop.
It turns out that the host kernel was providing a AT_SYSINFO_EHDR of
0xffffe000, which faked UML into believing that the host VDSO page could be
reused. However, AT_SYSINFO pointed into the middle of the address space, and
was unmapped as a result. Because UML was providing AT_SYSINFO_EHDR and
AT_SYSINFO to its own processes, these would branch to nowhere when trying to
use the VDSO.
The fix is to also check the location of AT_SYSINFO when deciding whether to
use the host's VDSO.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/um/os-Linux/elf_aux.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/um/os-Linux/elf_aux.c b/arch/um/os-Linux/elf_aux.c index 5a99dd3fbed0..13c6cb56e315 100644 --- a/arch/um/os-Linux/elf_aux.c +++ b/arch/um/os-Linux/elf_aux.c @@ -40,6 +40,9 @@ __init void scan_elf_aux( char **envp) switch ( auxv->a_type ) { case AT_SYSINFO: __kernel_vsyscall = auxv->a_un.a_val; + /* See if the page is under TASK_SIZE */ + if (__kernel_vsyscall < (unsigned long) envp) + __kernel_vsyscall = 0; break; case AT_SYSINFO_EHDR: vsyscall_ehdr = auxv->a_un.a_val; |