• Will Deacon's avatar
    perf/callchain: Force USER_DS when invoking perf_callchain_user() · 88b0193d
    Will Deacon authored
    Perf can generate and record a user callchain in response to a synchronous
    request, such as a tracepoint firing. If this happens under set_fs(KERNEL_DS),
    then we can end up walking the user stack (and dereferencing/saving whatever we
    find there) without the protections usually afforded by checks such as
    access_ok.
    
    Rather than play whack-a-mole with each architecture's stack unwinding
    implementation, fix the root of the problem by ensuring that we force USER_DS
    when invoking perf_callchain_user from the perf core.
    Reported-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
    Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
    Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    88b0193d
callchain.c 6.23 KB