When writing to procfs via `proc_write` fails, we try to chunk the
buffer into smaller pieces to work around that issue. When searching for
the next location to split the buffer, though, we can underflow the
buffer in case the current offset is smaller than `LINELEN`. Fix the
issue by passing `cookie->offset` instead of `LINELEN` into `memrchr` in
case `cookie->offset` is smaller than `LINELEN`.
This bug can be triggered on musl-based systems, e.g. by executing
$ sysctl kernel.printk_ratelimit=1000000000000000
As the value is out-of-range, `write` will return an error and set
`errno` to `EINVAL`. As we're only trying to write a smallish buffer
with a length smaller than `LINELEN` and as the buffer does not contain
any newlines, the call
token = (char*)memrchr(cookie->buf+offset, '\n', LINELEN);
will underflow the buffer and crash the program.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
The `fprocopen` function allows users to specify a delimiter chacter
that is used to split very large input lines into smaller chunks. While
the code checks that the caller did actually supply the delimiter, it is
in fact never used to split the string. Instead, the hardcoded default
character ',' is always used to split the string.
Fix the issue by using `cookie->delim` instead.
The only essential change was substituting 'comma' for
the word 'colon' in the man page plus program comment.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Duplicate that <libio.h> change made in master branch.
While we're at it, let's remove an unnecessary include
from procio.h and reflect in its single prototype what
those 'const char *' params are really supposed to be.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Now that the procio logic was removed from the library
we must move the header file, lest we break make dist.
In the process, we will relocate that source file too.
[ we'll take a slightly different approach than that ]
[ used under the master branch by exploiting those 2 ]
[ non-library directories 'include' and 'lib', while ]
[ avoiding any sysctl hard coded function prototype. ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
