commit fb7d1f41b409761be3381efaeec0f56d2a470a9f Author: teor (Tim Wilson-Brown) teor2345@gmail.com Date: Tue Jan 19 11:22:58 2016 +1100

Make memwipe() do nothing when passed a NULL pointer or zero size

Check size argument to memwipe() for underflow.

Closes bug #18089. Reported by "gk", patch by "teor". Bugfix on 0.2.3.25 and 0.2.4.6-alpha (#7352), commit 49dd5ef3 on 7 Nov 2012. --- changes/bug18089 | 6 ++++++ src/common/crypto.c | 8 ++++++++ 2 files changed, 14 insertions(+)

diff --git a/changes/bug18089 b/changes/bug18089 new file mode 100644 index 0000000..c1fb342 --- /dev/null +++ b/changes/bug18089 @@ -0,0 +1,6 @@ + o Minor fixes (security): + - Make memwipe() do nothing when passed a NULL pointer + or zero size. Check size argument to memwipe() for underflow. + Closes bug #18089. Reported by "gk", patch by "teor". + Bugfix on 0.2.3.25 and 0.2.4.6-alpha (#7352), + commit 49dd5ef3 on 7 Nov 2012. diff --git a/src/common/crypto.c b/src/common/crypto.c index 925beb3..f913917 100644 --- a/src/common/crypto.c +++ b/src/common/crypto.c @@ -2972,6 +2972,7 @@ secret_to_key(char *key_out, size_t key_out_len, const char *secret, /** * Destroy the <b>sz</b> bytes of data stored at <b>mem</b>, setting them to * the value <b>byte</b>. + * If <b>mem</b> is NULL or <b>sz</b> is zero, nothing happens. * * This function is preferable to memset, since many compilers will happily * optimize out memset() when they can convince themselves that the data being @@ -2989,6 +2990,13 @@ secret_to_key(char *key_out, size_t key_out_len, const char *secret, void memwipe(void *mem, uint8_t byte, size_t sz) { + if (mem == NULL || sz == 0) { + return; + } + + /* Data this large is likely to be an underflow. */ + tor_assert(sz < SIZE_T_CEILING); + /* Because whole-program-optimization exists, we may not be able to just * have this function call "memset". A smart compiler could inline it, then * eliminate dead memsets, and declare itself to be clever. */