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| author | Thomas Weißschuh <linux@weissschuh.net> | 2025-10-28 10:15:39 +0100 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2025-11-06 13:02:33 +0100 |
| commit | 70d52694b6a67ace517da44ce4071594fcccd1ee (patch) | |
| tree | b6d382f32b1224837aa48663e5dffdbb8ac1339e /arch/um | |
| parent | 83b4b44a2b05330d13a4432caae0b036f9621ea1 (diff) | |
| download | linux-70d52694b6a67ace517da44ce4071594fcccd1ee.tar.gz linux-70d52694b6a67ace517da44ce4071594fcccd1ee.tar.bz2 linux-70d52694b6a67ace517da44ce4071594fcccd1ee.zip | |
x86/um: Do not inherit vDSO from host
Inheriting the vDSO from the host is problematic. The values read
from the time functions will not be correct for the UML kernel.
Furthermore the start and end of the vDSO are not stable or
detectable by userspace. Specifically the vDSO datapages start
before AT_SYSINFO_EHDR and the vDSO itself is larger than a single page.
This codepath is only used on 32bit x86 UML. In my testing with both
32bit and 64bit hosts the passthrough functionality has always been
disabled anyways due to the checks against envp in scan_elf_aux().
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-4-e930063eff5f@weissschuh.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'arch/um')
| -rw-r--r-- | arch/um/os-Linux/elf_aux.c | 27 | ||||
| -rw-r--r-- | arch/um/os-Linux/user_syms.c | 6 |
2 files changed, 0 insertions, 33 deletions
diff --git a/arch/um/os-Linux/elf_aux.c b/arch/um/os-Linux/elf_aux.c index 9ee0e3199790..f8927a5959d8 100644 --- a/arch/um/os-Linux/elf_aux.c +++ b/arch/um/os-Linux/elf_aux.c @@ -20,31 +20,15 @@ typedef Elf32_auxv_t elf_auxv_t; /* These are initialized very early in boot and never changed */ char * elf_aux_platform; extern long elf_aux_hwcap; -unsigned long vsyscall_ehdr; -unsigned long vsyscall_end; -unsigned long __kernel_vsyscall; __init void scan_elf_aux( char **envp) { - long page_size = 0; elf_auxv_t * auxv; while ( *envp++ != NULL) ; for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) { 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; - /* See if the page is under TASK_SIZE */ - if (vsyscall_ehdr < (unsigned long) envp) - vsyscall_ehdr = 0; - break; case AT_HWCAP: elf_aux_hwcap = auxv->a_un.a_val; break; @@ -56,17 +40,6 @@ __init void scan_elf_aux( char **envp) elf_aux_platform = (char *) (long) auxv->a_un.a_val; break; - case AT_PAGESZ: - page_size = auxv->a_un.a_val; - break; } } - if ( ! __kernel_vsyscall || ! vsyscall_ehdr || - ! page_size || (vsyscall_ehdr % page_size) ) { - __kernel_vsyscall = 0; - vsyscall_ehdr = 0; - } - else { - vsyscall_end = vsyscall_ehdr + page_size; - } } diff --git a/arch/um/os-Linux/user_syms.c b/arch/um/os-Linux/user_syms.c index a310ae27b479..67f6112318b6 100644 --- a/arch/um/os-Linux/user_syms.c +++ b/arch/um/os-Linux/user_syms.c @@ -31,12 +31,6 @@ extern void *memset(void *, int, size_t); EXPORT_SYMBOL(memset); #endif -#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA -/* needed for __access_ok() */ -EXPORT_SYMBOL(vsyscall_ehdr); -EXPORT_SYMBOL(vsyscall_end); -#endif - #ifdef _FORTIFY_SOURCE extern int __sprintf_chk(char *str, int flag, size_t len, const char *format); EXPORT_SYMBOL(__sprintf_chk); |