18 Dec, 2014
1 commit
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It turns out that there's a lurking ABI issue. GCC, when
compiling this in a 32-bit program:struct user_desc desc = {
.entry_number = idx,
.base_addr = base,
.limit = 0xfffff,
.seg_32bit = 1,
.contents = 0, /* Data, grow-up */
.read_exec_only = 0,
.limit_in_pages = 1,
.seg_not_present = 0,
.useable = 0,
};will leave .lm uninitialized. This means that anything in the
kernel that reads user_desc.lm for 32-bit tasks is unreliable.Revert the .lm check in set_thread_area(). The value never did
anything in the first place.Fixes: 0e58af4e1d21 ("x86/tls: Disallow unusual TLS segments")
Signed-off-by: Andy Lutomirski
Acked-by: Thomas Gleixner
Cc: stable@vger.kernel.org # Only if 0e58af4e1d21 is backported
Cc: Linus Torvalds
Link: http://lkml.kernel.org/r/d7875b60e28c512f6a6fc0baf5714d58e7eaadbb.1418856405.git.luto@amacapital.net
Signed-off-by: Ingo Molnar
14 Dec, 2014
2 commits
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Users have no business installing custom code segments into the
GDT, and segments that are not present but are otherwise valid
are a historical source of interesting attacks.For completeness, block attempts to set the L bit. (Prior to
this patch, the L bit would have been silently dropped.)This is an ABI break. I've checked glibc, musl, and Wine, and
none of them look like they'll have any trouble.Note to stable maintainers: this is a hardening patch that fixes
no known bugs. Given the possibility of ABI issues, this
probably shouldn't be backported quickly.Signed-off-by: Andy Lutomirski
Acked-by: H. Peter Anvin
Cc: stable@vger.kernel.org # optional
Cc: Konrad Rzeszutek Wilk
Cc: Linus Torvalds
Cc: security@kernel.org
Cc: Willy Tarreau
Signed-off-by: Ingo Molnar -
Installing a 16-bit RW data segment into the GDT defeats espfix.
AFAICT this will not affect glibc, Wine, or dosemu at all.Signed-off-by: Andy Lutomirski
Acked-by: H. Peter Anvin
Cc: stable@vger.kernel.org
Cc: Konrad Rzeszutek Wilk
Cc: Linus Torvalds
Cc: security@kernel.org
Cc: Willy Tarreau
Signed-off-by: Ingo Molnar
04 Mar, 2013
1 commit
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... and switch i386 to HAVE_SYSCALL_WRAPPERS, killing open-coded
uses of asmlinkage_protect() in a bunch of syscalls.Signed-off-by: Al Viro
30 Mar, 2012
1 commit
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Pull x86 updates from Ingo Molnar.
This touches some non-x86 files due to the sanitized INLINE_SPIN_UNLOCK
config usage.Fixed up trivial conflicts due to just header include changes (removing
headers due to cpu_idle() merge clashing with the split).* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/apic/amd: Be more verbose about LVT offset assignments
x86, tls: Off by one limit check
x86/ioapic: Add io_apic_ops driver layer to allow interception
x86/olpc: Add debugfs interface for EC commands
x86: Merge the x86_32 and x86_64 cpu_idle() functions
x86/kconfig: Remove CONFIG_TR=y from the defconfigs
x86: Stop recursive fault in print_context_stack after stack overflow
x86/io_apic: Move and reenable irq only when CONFIG_GENERIC_PENDING_IRQ=y
x86/apic: Add separate apic_id_valid() functions for selected apic drivers
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
x86/kconfig: Update defconfigs
x86: Fix excessive MSR print out when show_msr is not specified
29 Mar, 2012
2 commits
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Disintegrate asm/system.h for X86.
Signed-off-by: David Howells
Acked-by: H. Peter Anvin
cc: x86@kernel.org -
These are used as offsets into an array of GDT_ENTRY_TLS_ENTRIES members
so GDT_ENTRY_TLS_ENTRIES is one past the end of the array.Signed-off-by: Dan Carpenter
Link: http://lkml.kernel.org/r/20120324075250.GA28258@elgon.mountain
Cc:
Signed-off-by: H. Peter Anvin
22 Jul, 2008
1 commit
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Declaring arch-dependent syscalls for x86 architecture
Signed-off-by: Jaswinder Singh
11 Apr, 2008
1 commit
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The prevent_tail_call() macro works around the problem of the compiler
clobbering argument words on the stack, which for asmlinkage functions
is the caller's (user's) struct pt_regs. The tail/sibling-call
optimization is not the only way that the compiler can decide to use
stack argument words as scratch space, which we have to prevent.
Other optimizations can do it too.Until we have new compiler support to make "asmlinkage" binding on the
compiler's own use of the stack argument frame, we have work around all
the manifestations of this issue that crop up.More cases seem to be prevented by also keeping the incoming argument
variables live at the end of the function. This makes their original
stack slots attractive places to leave those variables, so the compiler
tends not clobber them for something else. It's still no guarantee, but
it handles some observed cases that prevent_tail_call() did not.Signed-off-by: Roland McGrath
Signed-off-by: Linus Torvalds
01 Mar, 2008
1 commit
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Fix a kernel bug (vmware boot problem) reported by Tomasz Grobelny,
which occurs with certain .config variants and gccs.The x86 TLS cleanup in commit efd1ca52d04d2f6df337a3332cee56cd60e6d4c4
made the sys_set_thread_area and sys_get_thread_area functions ripe for
tail call optimization. If the compiler chooses to use it for them, it
can clobber the user trap frame because these are asmlinkage functions.Reported-by: Tomasz Grobelny
Signed-off-by: Roland McGrath
Signed-off-by: Ingo Molnar
30 Jan, 2008
6 commits
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This adds accessor functions in the user_regset style for the TLS data.
Signed-off-by: Roland McGrath
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
This cleans up the TLS code to use struct desc_struct and to separate the
encoding and installation magic from the interface wrappers.Signed-off-by: Roland McGrath
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
This patch makes get_desc_base() receive a struct desc_struct,
and then uses its internal fields to compute the base address.
This is done at both i386 and x86_64, and then it is moved
to common headerSigned-off-by: Glauber de Oliveira Costa
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
This patch introduces fill_ldt(), which populates a ldt descriptor
from a user_desc in once, instead of relying in the LDT_entry_a and
LDT_entry_b macrosSigned-off-by: Glauber de Oliveira Costa
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
This consolidates the four different places that implemented the same
encoding magic for the GDT-slot 32-bit TLS support. The old tls32.c was
renamed and is now only slightly modified to be the shared implementation.Signed-off-by: Roland McGrath
Cc: Andrew Morton
Cc: Zachary Amsden
Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
This renames arch/x86/ia32/tls32.c to arch/x86/kernel/tls.c, which does
nothing now but paves the way to consolidate this code for 32-bit too.Signed-off-by: Roland McGrath
Cc: Andrew Morton
Cc: Zachary Amsden
Signed-off-by: Thomas Gleixner
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner
