Messages in this thread | ![/](/images/icornerl.gif) | | From | Yuntao Wang <> | Subject | Re: [PATCH] init/main.c: Fix potential static_command_line memory overflow | Date | Thu, 11 Apr 2024 22:27:23 +0800 |
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On Thu, 11 Apr 2024 16:21:37 +0300, Mike Rapoport <rppt@kernel.org> wrote: > On Thu, Apr 11, 2024 at 09:23:47AM +0200, Geert Uytterhoeven wrote: > > CC Hiramatsu-san > > > > On Thu, Apr 11, 2024 at 5:25 AM Yuntao Wang <ytcoode@gmail.com> wrote: > > > We allocate memory of size 'xlen + strlen(boot_command_line) + 1' for > > > static_command_line, but the strings copied into static_command_line are > > > extra_command_line and command_line, rather than extra_command_line and > > > boot_command_line. > > > > > > When strlen(command_line) > strlen(boot_command_line), static_command_line > > > will overflow. > > Can this ever happen? > Did you observe the overflow or is this a theoretical bug?
I didn't observe the overflow, it's just a theoretical bug.
> > > Fixes: f5c7310ac73e ("init/main: add checks for the return value of memblock_alloc*()") > > f5c7310ac73e didn't have the logic for calculating allocation size, we > surely don't want to go back that far wiht Fixes.
Before commit f5c7310ac73e, the memory size allocated for static_command_line was 'strlen(command_line) + 1', but commit f5c7310ac73e changed this size to 'strlen(boot_command_line) + 1'. I think this should be wrong.
> > > Signed-off-by: Yuntao Wang <ytcoode@gmail.com> > > > --- > > > init/main.c | 8 +++++--- > > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > > > diff --git a/init/main.c b/init/main.c > > > index 2ca52474d0c3..a7b1f5f3e3b6 100644 > > > --- a/init/main.c > > > +++ b/init/main.c > > > @@ -625,11 +625,13 @@ static void __init setup_command_line(char *command_line) > > > if (extra_init_args) > > > ilen = strlen(extra_init_args) + 4; /* for " -- " */ > > > > > > - len = xlen + strlen(boot_command_line) + 1; > > > + len = xlen + strlen(boot_command_line) + ilen + 1; > > > > > > - saved_command_line = memblock_alloc(len + ilen, SMP_CACHE_BYTES); > > > + saved_command_line = memblock_alloc(len, SMP_CACHE_BYTES); > > > if (!saved_command_line) > > > - panic("%s: Failed to allocate %zu bytes\n", __func__, len + ilen); > > > + panic("%s: Failed to allocate %zu bytes\n", __func__, len); > > > + > > > + len = xlen + strlen(command_line) + 1; > > > > > > static_command_line = memblock_alloc(len, SMP_CACHE_BYTES); > > > if (!static_command_line) > > > > Gr{oetje,eeting}s, > > > > Geert > > > > -- > > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > > > In personal conversations with technical people, I call myself a hacker. But > > when I'm talking to journalists I just say "programmer" or something like that. > > -- Linus Torvalds > > -- > Sincerely yours, > Mike.
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