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authorJeff Dike <jdike@addtoit.com>2007-02-28 20:13:31 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-03-01 14:53:38 -0800
commit14251809b1921b1216568700f1be2f91a1cbb5c7 (patch)
tree7162d7623138be81cc733968bf69d0511011d21b /arch/um
parentcf2775f175128fc9fd7ffb88981e068d27bc85db (diff)
[PATCH] 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@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um')
-rw-r--r--arch/um/os-Linux/elf_aux.c3
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 3a8d7e3aae0..608784d4ec5 100644
--- a/arch/um/os-Linux/elf_aux.c
+++ b/arch/um/os-Linux/elf_aux.c
@@ -39,6 +39,9 @@ __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;