| Message ID | 20241204153923.401674-1-colin.i.king@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [next] io_uring/kbuf: fix unintentional sign extension on shift of reg.bgid | expand |
On Wed, 04 Dec 2024 15:39:23 +0000, Colin Ian King wrote: > Shifting reg.bgid << IORING_OFF_PBUF_SHIFT results in a promotion > from __u16 to a 32 bit signed integer, this is then sign extended > to a 64 bit unsigned long on 64 bit architectures. If reg.bgid is > greater than 0x7fff then this leads to a sign extended result where > all the upper 32 bits of mmap_offset are set to 1. Fix this by > casting reg.bgid to the same type as mmap_offset before performing > the shift. > > [...] Applied, thanks! [1/1] io_uring/kbuf: fix unintentional sign extension on shift of reg.bgid commit: e54fb80b57e4534ae91e65ea14cc66b9f21b4b7a Best regards,
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index e91260a6156b..15e5e6ec5968 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -640,7 +640,7 @@ int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) return -ENOMEM; } - mmap_offset = reg.bgid << IORING_OFF_PBUF_SHIFT; + mmap_offset = (unsigned long)reg.bgid << IORING_OFF_PBUF_SHIFT; ring_size = flex_array_size(br, bufs, reg.ring_entries); memset(&rd, 0, sizeof(rd));
Shifting reg.bgid << IORING_OFF_PBUF_SHIFT results in a promotion from __u16 to a 32 bit signed integer, this is then sign extended to a 64 bit unsigned long on 64 bit architectures. If reg.bgid is greater than 0x7fff then this leads to a sign extended result where all the upper 32 bits of mmap_offset are set to 1. Fix this by casting reg.bgid to the same type as mmap_offset before performing the shift. Fixes: ff4afde8a61f ("io_uring/kbuf: use region api for pbuf rings") Signed-off-by: Colin Ian King <colin.i.king@gmail.com> --- io_uring/kbuf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)