From b9f28d863594c429e1df35a0474d2663ca28b307 Mon Sep 17 00:00:00 2001 From: James Bottomley Date: Thu, 5 Mar 2015 18:47:01 -0800 Subject: sd, mmc, virtio_blk, string_helpers: fix block size units The current string_get_size() overflows when the device size goes over 2^64 bytes because the string helper routine computes the suffix from the size in bytes. However, the entirety of Linux thinks in terms of blocks, not bytes, so this will artificially induce an overflow on very large devices. Fix this by making the function string_get_size() take blocks and the block size instead of bytes. This should allow us to keep working until the current SCSI standard overflows. Also fix virtio_blk and mmc (both of which were also artificially multiplying by the block size to pass a byte side to string_get_size()). The mathematics of this is pretty simple: we're taking a product of size in blocks (S) and block size (B) and trying to re-express this in exponential form: S*B = R*N^E (where N, the exponent is either 1000 or 1024) and R < N. Mathematically, S = RS*N^ES and B=RB*N^EB, so if RS*RB < N it's easy to see that S*B = RS*RB*N^(ES+EB). However, if RS*BS > N, we can see that this can be re-expressed as RS*BS = R*N (where R = RS*BS/N < N) so the whole exponent becomes R*N^(ES+EB+1) [jejb: fix incorrect 32 bit do_div spotted by kbuild test robot ] Acked-by: Ulf Hansson Reviewed-by: Andrew Morton Signed-off-by: James Bottomley --- include/linux/string_helpers.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/string_helpers.h') diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h index 657571817260..263328063730 100644 --- a/include/linux/string_helpers.h +++ b/include/linux/string_helpers.h @@ -10,7 +10,7 @@ enum string_size_units { STRING_UNITS_2, /* use binary powers of 2^10 */ }; -void string_get_size(u64 size, enum string_size_units units, +void string_get_size(u64 size, u64 blk_size, enum string_size_units units, char *buf, int len); #define UNESCAPE_SPACE 0x01 -- cgit v1.2.3 From 41416f2330112d29f2cfa337bfc7e672bf0c2768 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Wed, 15 Apr 2015 16:17:28 -0700 Subject: lib/string_helpers.c: change semantics of string_escape_mem The current semantics of string_escape_mem are inadequate for one of its current users, vsnprintf(). If that is to honour its contract, it must know how much space would be needed for the entire escaped buffer, and string_escape_mem provides no way of obtaining that (short of allocating a large enough buffer (~4 times input string) to let it play with, and that's definitely a big no-no inside vsnprintf). So change the semantics for string_escape_mem to be more snprintf-like: Return the size of the output that would be generated if the destination buffer was big enough, but of course still only write to the part of dst it is allowed to, and (contrary to snprintf) don't do '\0'-termination. It is then up to the caller to detect whether output was truncated and to append a '\0' if desired. Also, we must output partial escape sequences, otherwise a call such as snprintf(buf, 3, "%1pE", "\123") would cause printf to write a \0 to buf[2] but leaving buf[0] and buf[1] with whatever they previously contained. This also fixes a bug in the escaped_string() helper function, which used to unconditionally pass a length of "end-buf" to string_escape_mem(); since the latter doesn't check osz for being insanely large, it would happily write to dst. For example, kasprintf(GFP_KERNEL, "something and then %pE", ...); is an easy way to trigger an oops. In test-string_helpers.c, the -ENOMEM test is replaced with testing for getting the expected return value even if the buffer is too small. We also ensure that nothing is written (by relying on a NULL pointer deref) if the output size is 0 by passing NULL - this has to work for kasprintf("%pE") to work. In net/sunrpc/cache.c, I think qword_add still has the same semantics. Someone should definitely double-check this. In fs/proc/array.c, I made the minimum possible change, but longer-term it should stop poking around in seq_file internals. [andriy.shevchenko@linux.intel.com: simplify qword_add] [andriy.shevchenko@linux.intel.com: add missed curly braces] Signed-off-by: Rasmus Villemoes Acked-by: Andy Shevchenko Signed-off-by: Andy Shevchenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/string_helpers.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux/string_helpers.h') diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h index 657571817260..0991913f4953 100644 --- a/include/linux/string_helpers.h +++ b/include/linux/string_helpers.h @@ -47,22 +47,22 @@ static inline int string_unescape_any_inplace(char *buf) #define ESCAPE_ANY_NP (ESCAPE_ANY | ESCAPE_NP) #define ESCAPE_HEX 0x20 -int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz, +int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz, unsigned int flags, const char *esc); static inline int string_escape_mem_any_np(const char *src, size_t isz, - char **dst, size_t osz, const char *esc) + char *dst, size_t osz, const char *esc) { return string_escape_mem(src, isz, dst, osz, ESCAPE_ANY_NP, esc); } -static inline int string_escape_str(const char *src, char **dst, size_t sz, +static inline int string_escape_str(const char *src, char *dst, size_t sz, unsigned int flags, const char *esc) { return string_escape_mem(src, strlen(src), dst, sz, flags, esc); } -static inline int string_escape_str_any_np(const char *src, char **dst, +static inline int string_escape_str_any_np(const char *src, char *dst, size_t sz, const char *esc) { return string_escape_str(src, dst, sz, ESCAPE_ANY_NP, esc); -- cgit v1.2.3