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Thomas Gleixner authored
commit 6fdc6dd9 upstream. The vsyscall32 sysctl can racy against a concurrent fork when it switches from disabled to enabled: arch_setup_additional_pages() if (vdso32_enabled) --> No mapping sysctl.vsysscall32() --> vdso32_enabled = true create_elf_tables() ARCH_DLINFO_IA32 if (vdso32_enabled) { --> Add VDSO entry with NULL pointer Make ARCH_DLINFO_IA32 check whether the VDSO mapping has been set up for the newly forked process or not. Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Acked-by:
Andy Lutomirski <luto@amacapital.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mathias Krause <minipli@googlemail.com> Link: http://lkml.kernel.org/r/20170410151723.602367196@linutronix.deSigned-off-by:
Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: change the flag passed to ARCH_DLINFO_IA32()] Signed-off-by:
Ben Hutchings <ben@decadent.org.uk>
df1c5dfd