commit db8156533133836b19bca51f7fabba4d161b6ba2
Author: teor (Tim Wilson-Brown) <teor2...@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 218c7be..4e0b383 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -3012,6 +3012,7 @@ base32_decode(char *dest, size_t destlen, const char
*src, size_t srclen)
/**
* 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
@@ -3029,6 +3030,13 @@ base32_decode(char *dest, size_t destlen, const char
*src, size_t srclen)
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. */
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