aboutsummaryrefslogtreecommitdiffstats
path: root/lib/strnlen_user.c (follow)
AgeCommit message (Collapse)AuthorFilesLines
2015-06-03lib: Clarify the return value of strnlen_user()Jan Kara1-1/+8
strnlen_user() can return a number in a range 0 to count + sizeof(unsigned long) - 1. Clarify the comment at the top of the function so that users don't think the function returns at most count+1. Signed-off-by: Jan Kara <jack@suse.cz> [ Also added commentary about preferably not using this function ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-02lib: Fix strnlen_user() to not touch memory after specified maximumJan Kara1-1/+2
If the specified maximum length of the string is a multiple of unsigned long, we would load one long behind the specified maximum. If that happens to be in a next page, we can hit a page fault although we were not expected to. Fix the off-by-one bug in the test whether we are at the end of the specified range. Signed-off-by: Jan Kara <jack@suse.cz> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-27lib: Fix generic strnlen_user for 32-bit big-endian machinesPaul Mackerras1-1/+1
The aligned_byte_mask() definition is wrong for 32-bit big-endian machines: the "7-(n)" part of the definition assumes a long is 8 bytes. This fixes it by using BITS_PER_LONG - 8 instead of 8*7. Tested on 32-bit and 64-bit PowerPC. Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-26lib: add generic strnlen_user() functionLinus Torvalds1-0/+138
This adds a new generic optimized strnlen_user() function that uses the <asm/word-at-a-time.h> infrastructure to portably do efficient string handling. In many ways, strnlen is much simpler than strncpy, and in particular we can always pre-align the words we load from memory. That means that all the worries about alignment etc are a non-issue, so this one can easily be used on any architecture. You obviously do have to do the appropriate word-at-a-time.h macros. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>