commit 52342327c7e566a25bf69dc6df651de45959e6d6 Author: Nick Mathewson nickm@torproject.org Date: Mon Sep 2 14:49:53 2019 -0400

madvise: tolerate EINVAL and ENOSYS

These errors can occur if we are built on a system with support for madvise(MADV_NOFORK) but then we are run on a system whose kernel does not support that flag.

If the error is something that we don't tolerate at all, we now log it before crashing.

Fixes bug 31570. I am calling this a bugfix on 0.4.1.1-alpha, where we actually started using the map_anon code. --- changes/bug31570 | 5 +++++ src/lib/malloc/map_anon.c | 15 ++++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/changes/bug31570 b/changes/bug31570 new file mode 100644 index 000000000..f70b577b4 --- /dev/null +++ b/changes/bug31570 @@ -0,0 +1,5 @@ + o Major bugfixes (crash, android): + - Tolerate systems (including some Android installations) where madvise + and MADV_DONTDUMP are available at build-time, but not at run time. + Previously, these systems would notice a failed syscall and abort. + Fixes bug 31570; bugfix on 0.4.1.1-alpha. diff --git a/src/lib/malloc/map_anon.c b/src/lib/malloc/map_anon.c index 0f6a4150c..79bbb99f7 100644 --- a/src/lib/malloc/map_anon.c +++ b/src/lib/malloc/map_anon.c @@ -27,6 +27,9 @@ #include <windows.h> #endif

+#include <string.h> +#include <errno.h> + /** * Macro to get the high bytes of a size_t, if there are high bytes. * Windows needs this; other operating systems define a size_t that does @@ -108,7 +111,17 @@ static int nodump_mem(void *mem, size_t sz) { #if defined(MADV_DONTDUMP) - return madvise(mem, sz, MADV_DONTDUMP); + int rv = madvise(mem, sz, MADV_DONTDUMP); + if (rv == 0) { + return 0; + } else if (errno == ENOSYS || errno == EINVAL) { + return 0; // syscall not supported, or flag not supported. + } else { + tor_log_err_sigsafe("Unexpected error from madvise: ", + strerror(errno), + NULL); + return -1; + } #else (void) mem; (void) sz;