diff options
author | Daniel Borkmann <dborkman@redhat.com> | 2014-08-26 23:16:35 -0400 |
---|---|---|
committer | Zefan Li <lizefan@huawei.com> | 2015-02-02 17:04:54 +0800 |
commit | 6a16b0d080cd68ffac3f063891612dd9725a6d93 (patch) | |
tree | e2d9c64fbe93bc2c253e0a3e40708f4a3f2bcdef /include | |
parent | e4425815a8d45e730f3a0bd52b149ab65bbad73b (diff) |
random: add and use memzero_explicit() for clearing data
commit d4c5efdb97773f59a2b711754ca0953f24516739 upstream.
zatimend has reported that in his environment (3.16/gcc4.8.3/corei7)
memset() calls which clear out sensitive data in extract_{buf,entropy,
entropy_user}() in random driver are being optimized away by gcc.
Add a helper memzero_explicit() (similarly as explicit_bzero() variants)
that can be used in such cases where a variable with sensitive data is
being cleared out in the end. Other use cases might also be in crypto
code. [ I have put this into lib/string.c though, as it's always built-in
and doesn't need any dependencies then. ]
Fixes kernel bugzilla: 82041
Reported-by: zatimend@hotmail.co.uk
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[lizf: Backported to 3.4:
- adjust context
- another memset() in extract_buf() needs to be converted]
Signed-off-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/string.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index e033564f10ba..3d9feb70dc20 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -133,7 +133,7 @@ int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4); #endif extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, - const void *from, size_t available); + const void *from, size_t available); /** * strstarts - does @str start with @prefix? @@ -144,5 +144,7 @@ static inline bool strstarts(const char *str, const char *prefix) { return strncmp(str, prefix, strlen(prefix)) == 0; } + +void memzero_explicit(void *s, size_t count); #endif #endif /* _LINUX_STRING_H_ */ |