linux/lib/vsprintf.c, branch v4.5

vsprintf: kptr_restrict is okay in IRQ when 2

2016-02-12T02:35:48Z

The kptr_restrict flag, when set to 1, only prints the kernel address when the user has CAP_SYSLOG. When it is set to 2, the kernel address is always printed as zero. When set to 1, this needs to check whether or not we're in IRQ. However, when set to 2, this check is unneccessary, and produces confusing results in dmesg. Thus, only make sure we're not in IRQ when mode 1 is used, but not mode 2. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Jason A. Donenfeld Cc: Rasmus Villemoes Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf: factor out %pN[F] handler as netdev_bits()

2016-01-16T19:17:30Z

Move switch case to the netdev_features_string() and rename it to netdev_bits(). In the future we can extend it as needed. Here we replace the fallback of %pN from '%p' with possible flags to sticter '0x%p' without any flags variation. Signed-off-by: Andy Shevchenko Cc: Rasmus Villemoes Cc: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf: refactor duplicate code to special_hex_number()

2016-01-16T19:17:30Z

special_hex_number() is a helper to print a fixed size type in a hex format with '0x' prefix, zero padding, and small letters. In the module we have already several copies of such code. Consolidate them under special_hex_number() helper. There are couple of differences though. It seems nobody cared about the output in case of CONFIG_KALLSYMS=n, when printing symbol address, because the asked field width is not enough to care last 2 characters in the string represantation of the pointer. Fixed here. The %pNF specifier used to be allowed with a specific field width, though there is neither any user of it nor mention the possibility in the documentation. Signed-off-by: Andy Shevchenko Cc: Rasmus Villemoes Cc: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf.c: warn about too large precisions and field widths

2016-01-16T19:17:27Z

The field width is overloaded to pass some extra information for some %p extensions (e.g. #bits for %pb). But we might silently truncate the passed value when we stash it in struct printf_spec (see e.g. "lib/vsprintf.c: expand field_width to 24 bits"). Hopefully 23 value bits should now be enough for everybody, but if not, let's make some noise. Do the same for the precision. In both cases, clamping seems more sensible than truncating. While, according to POSIX, "A negative precision is taken as if the precision were omitted.", the kernel's printf has always treated that case as if the precision was 0, so we use that as lower bound. For the field width, the smallest representable value is actually -(1<<23), but a negative field width means 'set the LEFT flag and use the absolute value', so we want the absolute value to fit. Signed-off-by: Rasmus Villemoes Cc: Al Viro Cc: Andy Shevchenko Cc: Ingo Molnar Cc: Joe Perches Cc: Kees Cook Cc: Maurizio Lombardi Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf.c: help gcc make number() smaller

2016-01-16T19:17:26Z

One consequence of the reorganization of struct printf_spec to make field_width 24 bits was that number() gained about 180 bytes. Since spec is never passed to other functions, we can help gcc make number() lose most of that extra weight by using local variables for the field width and precision. Reviewed-by: Andy Shevchenko Signed-off-by: Rasmus Villemoes Cc: Al Viro Cc: Ingo Molnar Cc: Joe Perches Cc: Kees Cook Cc: Maurizio Lombardi Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf.c: expand field_width to 24 bits

2016-01-16T19:17:26Z

Maurizio Lombardi reported a problem [1] with the %pb extension: It doesn't work for sufficiently large bitmaps, since the size is stashed in the field_width field of the struct printf_spec, which is currently an s16. Concretely, this manifested itself in /sys/bus/pseudo/drivers/scsi_debug/map being empty, since the bitmap printer got a size of 0, which is the 16 bit truncation of the actual bitmap size. We do want to keep struct printf_spec at 8 bytes so that it can cheaply be passed by value. The qualifier field is only used for internal bookkeeping in format_decode, so we might as well use a local variable for that. This gives us an additional 8 bits, which we can then use for the field width. To stay in 8 bytes, we need to do a little rearranging and make the type member a bitfield as well. For consistency, change all the members to bit fields. gcc doesn't generate much worse code with these changes (in fact, bloat-o-meter says we save 300 bytes - which I think is a little surprising). I didn't find a BUILD_BUG/compiletime_assertion/... which would work outside function context, so for now I just open-coded it. [1] http://thread.gmane.org/gmane.linux.kernel/2034835 [akpm@linux-foundation.org: avoid open-coded BUILD_BUG_ON] Signed-off-by: Rasmus Villemoes Reported-by: Maurizio Lombardi Acked-by: Tejun Heo Cc: Al Viro Cc: Andy Shevchenko Cc: Ingo Molnar Cc: Joe Perches Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf.c: eliminate potential race in string()

2016-01-16T19:17:26Z

If the string corresponding to a %s specifier can change under us, we might end up copying a \0 byte to the output buffer. There might be callers who expect the output buffer to contain a genuine C string whose length is exactly the snprintf return value (assuming truncation hasn't happened or has been checked for). We can avoid this by only passing over the source string once, stopping the first time we meet a nul byte (or when we reach the given precision), and then letting widen_string() handle left/right space padding. As a small bonus, this code reuse also makes the generated code slightly smaller. Signed-off-by: Rasmus Villemoes Cc: Al Viro Cc: Andy Shevchenko Cc: Ingo Molnar Cc: Joe Perches Cc: Kees Cook Cc: Maurizio Lombardi Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf.c: move string() below widen_string()

2016-01-16T19:17:26Z

This is pure code movement, making sure the widen_string() helper is defined before the string() function. Signed-off-by: Rasmus Villemoes Cc: Al Viro Cc: Andy Shevchenko Cc: Ingo Molnar Cc: Joe Perches Cc: Kees Cook Cc: Maurizio Lombardi Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf.c: pull out padding code from dentry_name()

2016-01-16T19:17:25Z

Pull out the logic in dentry_name() which handles field width space padding, in preparation for reusing it from string(). Rename the widen() helper to move_right(), since it is used for handling the !(flags & LEFT) case. Signed-off-by: Rasmus Villemoes Cc: Al Viro Cc: Andy Shevchenko Cc: Ingo Molnar Cc: Joe Perches Cc: Kees Cook Cc: Maurizio Lombardi Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lib/vsprintf: add %*pg format specifier

2016-01-06T17:55:29Z

This allow to directly print block_device name. Currently one should use bdevname() with temporal char buffer. This is very ineffective because bloat stack usage for deep IO call-traces Example: %pg -> sda, sda1 or loop0p1 [AV: fixed a minor braino - position updates should not be dependent upon having reached the of buffer] Signed-off-by: Dmitry Monakhov Signed-off-by: Al Viro