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linux-user: Emulate /proc/self/maps under mmap_lock

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If one thread modifies the mappings and another thread prints them,
a situation may occur that the printer thread sees a guest mapping
without a corresponding host mapping, leading to a crash in
open_self_maps_2().

Cc: qemu-stable@nongnu.org
Fixes: 7b7a3366e142 ("linux-user: Use walk_memory_regions for open_self_maps")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20241014203441.387560-1-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit bbd5630a75e70a0f1bcf04de74c94aa94a145628)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: context fix in linux-user/syscall.c due to missing v9.0.0-421-g59272469bd13
 "user: Use get_task_state() helper")
This commit is contained in:
Ilya Leoshkevich 2024-10-14 22:34:21 +02:00 committed by Michael Tokarev
parent 893e7f2b39
commit 05d635a28d
1 changed files with 3 additions and 1 deletions
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4
linux-user/syscall.c
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@ -8132,17 +8132,19 @@ static int open_self_maps_1(CPUArchState *env, int fd, bool smaps)
{ {
struct open_self_maps_data d = { struct open_self_maps_data d = {
.ts = env_cpu(env)->opaque, .ts = env_cpu(env)->opaque,
.host_maps = read_self_maps(),
.fd = fd, .fd = fd,
.smaps = smaps .smaps = smaps
}; };
mmap_lock();
d.host_maps = read_self_maps();
if (d.host_maps) { if (d.host_maps) {
walk_memory_regions(&d, open_self_maps_2); walk_memory_regions(&d, open_self_maps_2);
free_self_maps(d.host_maps); free_self_maps(d.host_maps);
} else { } else {
walk_memory_regions(&d, open_self_maps_3); walk_memory_regions(&d, open_self_maps_3);
} }
mmap_unlock();
return 0; return 0;
} }