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BUG/MINOR: pools: don't mark the thread harmless if already isolated

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Commit 85b2cae63 ("MINOR: pools: make the thread harmless during the
mmap/munmap syscalls") was used to relax the pressure experienced by
other threads when running in debug mode with UAF enabled. It places
a pair of thread_harmless_now()/thread_harmless_end() around the call
to mmap(), assuming callers are not sensitive to parallel activity.
But there are a few cases like "show sess all" where this happens in
isolated threads, and marking the thread as harmless there is a very
bad idea, even worse when arriving to thread_harmless_end() which loops
forever.

Let's only do that when the thread is not isolated. No backport is
needed as the patch above was only in 2.1-dev.
This commit is contained in:
Willy Tarreau 2019-08-08 07:38:19 +02:00
parent c9858010c2
commit 229e739c21
1 changed files with 6 additions and 2 deletions
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8
include/common/memory.h
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@ -416,9 +416,12 @@ static inline void pool_free_area(void *area, size_t __maybe_unused size)
static inline void *pool_alloc_area(size_t size)
{
size_t pad = (4096 - size) & 0xFF0;
int isolated;
void *ret;
thread_harmless_now();
isolated = thread_isolated();
if (!isolated)
thread_harmless_now();
ret = mmap(NULL, (size + 4095) & -4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (ret != MAP_FAILED) {
/* let's dereference the page before returning so that the real
@ -431,7 +434,8 @@ static inline void *pool_alloc_area(size_t size)
} else {
ret = NULL;
}
thread_harmless_end();
if (!isolated)
thread_harmless_end();
return ret;
}