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| author | Daniel Borkmann <dborkman@redhat.com> | 2014-08-27 07:16:35 +0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-10-17 19:37:29 +0400 |
| commit | d4c5efdb97773f59a2b711754ca0953f24516739 (patch) | |
| tree | 83ededeb92d6d529e8081b97b2f9cdf491094b78 /include/linux | |
| parent | 7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 (diff) | |
| download | linux-d4c5efdb97773f59a2b711754ca0953f24516739.tar.xz | |
random: add and use memzero_explicit() for clearing data
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>
Cc: stable@vger.kernel.org
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/string.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index d36977e029af..3b42b3732da6 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -132,7 +132,7 @@ 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? @@ -144,7 +144,8 @@ static inline bool strstarts(const char *str, const char *prefix) return strncmp(str, prefix, strlen(prefix)) == 0; } -extern size_t memweight(const void *ptr, size_t bytes); +size_t memweight(const void *ptr, size_t bytes); +void memzero_explicit(void *s, size_t count); /** * kbasename - return the last part of a pathname. |