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x86/insn, tools/x86: Fix undefined behavior due to potential unaligned accesses

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Don't perform unaligned loads in __get_next() and __peek_nbyte_next() as
these are forms of undefined behavior:

"A pointer to an object or incomplete type may be converted to a pointer
to a different object or incomplete type. If the resulting pointer
is not correctly aligned for the pointed-to type, the behavior is
undefined."

(from http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf)

These problems were identified using the undefined behavior sanitizer
(ubsan) with the tools version of the code and perf test.

 [ bp: Massage commit message. ]

Signed-off-by: Numfor Mbiziwo-Tiapo <[email protected]>
Signed-off-by: Ian Rogers <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
This commit is contained in:
Numfor Mbiziwo-Tiapo authored and Borislav Petkov committed 2021-09-24 12:37:38 +02:00
1 parent d81ff5fe14
commit 5ba1071f75
2 files changed
+4 -4
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arch/x86/lib/insn.c
+2 -2
View File
@@ -37,10 +37,10 @@
((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
#define __get_next(t, insn) \
({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
({ t r; memcpy(&r, insn->next_byte, sizeof(t)); insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
#define __peek_nbyte_next(t, insn, n) \
({ t r = *(t*)((insn)->next_byte + n); leXX_to_cpu(t, r); })
({ t r; memcpy(&r, (insn)->next_byte + n, sizeof(t)); leXX_to_cpu(t, r); })
#define get_next(t, insn) \
({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
tools/arch/x86/lib/insn.c
+2 -2
View File
@@ -37,10 +37,10 @@
((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
#define __get_next(t, insn) \
({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
({ t r; memcpy(&r, insn->next_byte, sizeof(t)); insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
#define __peek_nbyte_next(t, insn, n) \
({ t r = *(t*)((insn)->next_byte + n); leXX_to_cpu(t, r); })
({ t r; memcpy(&r, (insn)->next_byte + n, sizeof(t)); leXX_to_cpu(t, r); })
#define get_next(t, insn) \
({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })