On Fri, Mar 12, 2021 at 12:55:58PM -0800, Kees Cook wrote: > The sysfs interface to seq_file continues to be rather fragile, as seen > with some recent exploits[1]. Move the seq_file buffer to the vmap area > (while retaining the accounting flag), since it has guard pages that > will catch and stop linear overflows. This seems justified given that > seq_file already uses kvmalloc(), that allocations are normally short > lived, and that they are not normally performance critical. > > [1] https://blog.grimm-co.com/2021/03/new-old-bugs-in-linux-kernel.html > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > fs/seq_file.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/fs/seq_file.c b/fs/seq_file.c > index cb11a34fb871..ad78577d4c2c 100644 > --- a/fs/seq_file.c > +++ b/fs/seq_file.c > @@ -32,7 +32,7 @@ static void seq_set_overflow(struct seq_file *m) > > static void *seq_buf_alloc(unsigned long size) > { > - return kvmalloc(size, GFP_KERNEL_ACCOUNT); > + return __vmalloc(size, GFP_KERNEL_ACCOUNT); Maybe a small comment here like: /* use vmalloc as it has good bounds checking */ so we know why this is being used instead of kmalloc() or anything else? Other than that, no objection from me: Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
