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io_uring/memmap: don't use page_address() on a highmem page 

For older/32-bit systems with highmem, don't assume that the pages in
a mapped region are always going to be mapped. If io_region_init_ptr()
finds that the pages are coalescable, also check if the first page is
a HighMem page or not. If it is, fall through to the usual vmap()
mapping rather than attempt to get the unmapped page address.

Cc: stable@vger.kernel.org
Fixes: c4d0ac1c15 ("io_uring/memmap: optimise single folio regions")
Link: https://lore.kernel.org/all/681fe2fb.050a0220.f2294.001a.GAE@google.com/
Reported-by: syzbot+5b8c4abafcb1d791ccfc@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/681fed0a.050a0220.f2294.001c.GAE@google.com/
Reported-by: syzbot+6456a99dfdc2e78c4feb@syzkaller.appspotmail.com
Tested-by: syzbot+6456a99dfdc2e78c4feb@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
pull/1237/head
Jens Axboe 2025-05-12 09:06:06 -06:00
parent 63166b815d
commit f446c6311e
1 changed files with 1 additions and 1 deletions
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2
io_uring/memmap.c
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@ -116,7 +116,7 @@ static int io_region_init_ptr(struct io_mapped_region *mr)
void *ptr;
if (io_check_coalesce_buffer(mr->pages, mr->nr_pages, &ifd)) {
if (ifd.nr_folios == 1) {
if (ifd.nr_folios == 1 && !PageHighMem(mr->pages[0])) {
mr->ptr = page_address(mr->pages[0]);
return 0;
}