• Lennert Buytenhek's avatar
    [ARM] 5340/1: fix stack placement after noexecstack changes · 794baba6
    Lennert Buytenhek authored
    Commit 8ec53663 ("[ARM] Improve
    non-executable support") added support for detecting non-executable
    stack binaries.  One of the things it does is to make READ_IMPLIES_EXEC
    be set in ->personality if we are running on a CPU that doesn't support
    the XN ("Execute Never") page table bit or if we are running a binary
    that needs an executable stack.
    
    This exposed a latent bug in ARM's asm/processor.h due to which we'll
    end up placing the stack at a very low address, where it will bump into
    the heap on any application that uses significant amount of stack or
    heap or both, causing many interesting crashes.
    
    Fix this by testing the ADDR_LIMIT_32BIT bit in ->personality instead
    of testing for equality against PER_LINUX_32BIT.
    Reviewed-by: default avatarNicolas Pitre <nico@marvell.com>
    Signed-off-by: default avatarLennert Buytenhek <buytenh@marvell.com>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    794baba6
processor.h 2.9 KB