From: Cyrill Gorcunov <gorcunov@gmail.com> To: tml <tarantool-patches@dev.tarantool.org> Subject: [Tarantool-patches] [PATCH v2 2/2] fiber: exit with panic if we unable to revert guard page Date: Wed, 15 Jan 2020 20:05:24 +0300 [thread overview] Message-ID: <20200115170524.20471-3-gorcunov@gmail.com> (raw) In-Reply-To: <20200115170524.20471-1-gorcunov@gmail.com> At the moment we setup fiber's stack with a guard page which is used to detect stack overrun. This page is just a regular page taken from a slab with PROT_NONE attribute. Once fiber is no longer needed we try to revert this attribute back to PROT_READ | PROT_WRITE. Still there is a pretty small chance that this attempt get failed. Thus in such case we should not allow to proceed but rather lets panic, otherwise the slab won't longer be solid r/w memory area and attempt to write into this page will cause an unpredictable exception. Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> --- src/lib/core/fiber.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/lib/core/fiber.c b/src/lib/core/fiber.c index b51f46f2f..fdad7607c 100644 --- a/src/lib/core/fiber.c +++ b/src/lib/core/fiber.c @@ -1041,13 +1041,17 @@ fiber_stack_destroy(struct fiber *fiber, struct slab_cache *slabc) * to setup the original protection back in * background. * + * For now lets exit with panic: if mprotect + * failed we must not allow to reuse such slab + * with PROT_NONE'ed page somewhere inside. + * * Note that in case if we're called from * fiber_stack_create() the @mprotect_flags is * the same as the slab been created with, so * calling mprotect for VMA with same flags * won't fail. */ - diag_log(); + panic_syserror("fiber: Can't put guard page to slab"); } slab_put(slabc, fiber->stack_slab); } -- 2.20.1
next prev parent reply other threads:[~2020-01-15 17:05 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-15 17:05 [Tarantool-patches] [PATCH v2 0/2] fiber: Handle stack madvise/mprotect errors Cyrill Gorcunov 2020-01-15 17:05 ` [Tarantool-patches] [PATCH v2 1/2] fiber: use diag_ logger in fiber_madvise/mprotect failures Cyrill Gorcunov 2020-02-03 21:56 ` Alexander Turenko 2020-02-03 22:05 ` Cyrill Gorcunov 2020-02-03 22:10 ` Alexander Turenko 2020-01-15 17:05 ` Cyrill Gorcunov [this message] 2020-02-03 22:03 ` [Tarantool-patches] [PATCH v2 2/2] fiber: exit with panic if we unable to revert guard page Alexander Turenko 2020-02-04 15:47 ` Konstantin Osipov 2020-02-04 16:08 ` Cyrill Gorcunov
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