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| author | David Howells <dhowells@redhat.com> | 2022-03-21 08:11:52 +0000 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2022-03-21 12:43:47 +0000 |
| commit | a635415a064e77bcfbf43da413fd9dfe0bbed9cb (patch) | |
| tree | 420df204d7fb28b2c07e255d182820a938d662e3 /kernel/watch_queue.c | |
| parent | f443e374ae131c168a065ea1748feac6b2e76613 (diff) | |
| download | lwn-a635415a064e77bcfbf43da413fd9dfe0bbed9cb.tar.gz lwn-a635415a064e77bcfbf43da413fd9dfe0bbed9cb.zip | |
watch_queue: Fix NULL dereference in error cleanup
In watch_queue_set_size(), the error cleanup code doesn't take account of
the fact that __free_page() can't handle a NULL pointer when trying to free
up buffer pages that did get allocated.
Fix this by only calling __free_page() on the pages actually allocated.
Without the fix, this can lead to something like the following:
BUG: KASAN: null-ptr-deref in __free_pages+0x1f/0x1b0 mm/page_alloc.c:5473
Read of size 4 at addr 0000000000000034 by task syz-executor168/3599
...
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
__kasan_report mm/kasan/report.c:446 [inline]
kasan_report.cold+0x66/0xdf mm/kasan/report.c:459
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
instrument_atomic_read include/linux/instrumented.h:71 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
page_ref_count include/linux/page_ref.h:67 [inline]
put_page_testzero include/linux/mm.h:717 [inline]
__free_pages+0x1f/0x1b0 mm/page_alloc.c:5473
watch_queue_set_size+0x499/0x630 kernel/watch_queue.c:275
pipe_ioctl+0xac/0x2b0 fs/pipe.c:632
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Reported-and-tested-by: syzbot+d55757faa9b80590767b@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Diffstat (limited to 'kernel/watch_queue.c')
| -rw-r--r-- | kernel/watch_queue.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c index 00703444a219..5848d4795816 100644 --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -271,7 +271,7 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes) return 0; error_p: - for (i = 0; i < nr_pages; i++) + while (--i >= 0) __free_page(pages[i]); kfree(pages); error: |