4731f89b3b
Fixes the appended use-after-free. The root cause is that
during tb invalidation we use CPU_FOREACH, and therefore
to safely free a vCPU we must wait for an RCU grace period
to elapse.
$ x86_64-linux-user/qemu-x86_64 tests/tcg/x86_64-linux-user/munmap-pthread
=================================================================
==1800604==ERROR: AddressSanitizer: heap-use-after-free on address 0x62d0005f7418 at pc 0x5593da6704eb bp 0x7f4961a7ac70 sp 0x7f4961a7ac60
READ of size 8 at 0x62d0005f7418 thread T2
#0 0x5593da6704ea in tb_jmp_cache_inval_tb ../accel/tcg/tb-maint.c:244
#1 0x5593da6704ea in do_tb_phys_invalidate ../accel/tcg/tb-maint.c:290
#2 0x5593da670631 in tb_phys_invalidate__locked ../accel/tcg/tb-maint.c:306
#3 0x5593da670631 in tb_invalidate_phys_page_range__locked ../accel/tcg/tb-maint.c:542
#4 0x5593da67106d in tb_invalidate_phys_range ../accel/tcg/tb-maint.c:614
#5 0x5593da6a64d4 in target_munmap ../linux-user/mmap.c:766
#6 0x5593da6dba05 in do_syscall1 ../linux-user/syscall.c:10105
#7 0x5593da6f564c in do_syscall ../linux-user/syscall.c:13329
#8 0x5593da49e80c in cpu_loop ../linux-user/x86_64/../i386/cpu_loop.c:233
#9 0x5593da6be28c in clone_func ../linux-user/syscall.c:6633
#10 0x7f496231cb42 in start_thread nptl/pthread_create.c:442
#11 0x7f49623ae9ff (/lib/x86_64-linux-gnu/libc.so.6+0x1269ff)
0x62d0005f7418 is located 28696 bytes inside of 32768-byte region [0x62d0005f0400,0x62d0005f8400)
freed by thread T148 here:
#0 0x7f49627b6460 in __interceptor_free ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:52
#1 0x5593da5ac057 in cpu_exec_unrealizefn ../cpu.c:180
#2 0x5593da81f851 (/home/cota/src/qemu/build/qemu-x86_64+0x484851)
Signed-off-by: Emilio Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230111151628.320011-2-cota@braap.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230124180127.1881110-27-alex.bennee@linaro.org>
67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
/*
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* The per-CPU TranslationBlock jump cache.
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#ifndef ACCEL_TCG_TB_JMP_CACHE_H
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#define ACCEL_TCG_TB_JMP_CACHE_H
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#define TB_JMP_CACHE_BITS 12
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#define TB_JMP_CACHE_SIZE (1 << TB_JMP_CACHE_BITS)
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/*
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* Accessed in parallel; all accesses to 'tb' must be atomic.
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* For TARGET_TB_PCREL, accesses to 'pc' must be protected by
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* a load_acquire/store_release to 'tb'.
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*/
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struct CPUJumpCache {
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struct rcu_head rcu;
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struct {
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TranslationBlock *tb;
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#if TARGET_TB_PCREL
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target_ulong pc;
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#endif
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} array[TB_JMP_CACHE_SIZE];
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};
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static inline TranslationBlock *
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tb_jmp_cache_get_tb(CPUJumpCache *jc, uint32_t hash)
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{
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#if TARGET_TB_PCREL
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/* Use acquire to ensure current load of pc from jc. */
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return qatomic_load_acquire(&jc->array[hash].tb);
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#else
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/* Use rcu_read to ensure current load of pc from *tb. */
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return qatomic_rcu_read(&jc->array[hash].tb);
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#endif
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}
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static inline target_ulong
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tb_jmp_cache_get_pc(CPUJumpCache *jc, uint32_t hash, TranslationBlock *tb)
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{
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#if TARGET_TB_PCREL
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return jc->array[hash].pc;
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#else
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return tb_pc(tb);
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#endif
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}
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static inline void
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tb_jmp_cache_set(CPUJumpCache *jc, uint32_t hash,
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TranslationBlock *tb, target_ulong pc)
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{
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#if TARGET_TB_PCREL
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jc->array[hash].pc = pc;
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/* Use store_release on tb to ensure pc is written first. */
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qatomic_store_release(&jc->array[hash].tb, tb);
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#else
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/* Use the pc value already stored in tb->pc. */
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qatomic_set(&jc->array[hash].tb, tb);
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#endif
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}
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#endif /* ACCEL_TCG_TB_JMP_CACHE_H */
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