ich777/linux_media
1
0
Fork 0
mirror of https://github.com/tbsdtv/linux_media.git synced 2025-07-23 12:43:29 +02:00
Code Issues Packages Projects Releases Wiki Activity

random: add and use memzero_explicit() for clearing data

Browse Source 
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
This commit is contained in:
Daniel Borkmann
2014-08-26 23:16:35 -04:00
committed by Theodore Ts'o
parent 7d1311b93e
commit d4c5efdb97
3 changed files with 23 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/string.h
View File

@@ -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.