On Thu, Jun 10, 2021 at 10:29:59AM -0400, Qian Cai wrote: > Al, a quick fuzzing on today's linux-next triggered this. I never saw this before, so I am wondering if this is anything to do with this series. I could try to narrow it down and bisect if necessary. Any thoughts? Do you have a reproducer? > [ 1904.633865][T14444] BUG: KASAN: stack-out-of-bounds in iov_iter_revert+0x65c/0x760 > [ 1904.641445][T14444] Read of size 8 at addr ffff80002692faf8 by task trinity-c30/14444 > [ 1904.649275][T14444] > [ 1904.651461][T14444] CPU: 28 PID: 14444 Comm: trinity-c30 Not tainted 5.13.0-rc5-next-20210610+ #24 > [ 1904.660419][T14444] Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.6 06/28/2020 > [ 1904.668944][T14444] Call trace: > [ 1904.672084][T14444] dump_backtrace+0x0/0x3b8 > [ 1904.676445][T14444] show_stack+0x20/0x30 > [ 1904.680454][T14444] dump_stack_lvl+0x144/0x190 > [ 1904.684987][T14444] print_address_description.constprop.0+0xd0/0x3c8 > [ 1904.691432][T14444] kasan_report+0x1f0/0x208 > [ 1904.695787][T14444] __asan_report_load8_noabort+0x34/0x60 > [ 1904.701274][T14444] iov_iter_revert+0x65c/0x760 > iov_iter_revert at /usr/src/linux-next/lib/iov_iter.c:1118 *blink* <checks -next> Ah, the line numbers are shifted by gfs2 stuff. > (inlined by) iov_iter_revert at /usr/src/linux-next/lib/iov_iter.c:1058 > [ 1904.705891][T14444] netlink_sendmsg+0x870/0xa18 > netlink_sendmsg at /usr/src/linux-next/net/netlink/af_netlink.c:1913 call of memcpy_from_skb(), calling copy_from_iter_full(), which calls iov_iter_revert() on failure now... Bloody hell. Incremental, to be folded in: diff --git a/include/linux/uio.h b/include/linux/uio.h index fd88d9911dad..82c3c3e819e0 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -154,7 +154,7 @@ bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i) size_t copied = copy_from_iter(addr, bytes, i); if (likely(copied == bytes)) return true; - iov_iter_revert(i, bytes - copied); + iov_iter_revert(i, copied); return false; } @@ -173,7 +173,7 @@ bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i) size_t copied = copy_from_iter_nocache(addr, bytes, i); if (likely(copied == bytes)) return true; - iov_iter_revert(i, bytes - copied); + iov_iter_revert(i, copied); return false; } @@ -282,7 +282,7 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes, size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i); if (likely(copied == bytes)) return true; - iov_iter_revert(i, bytes - copied); + iov_iter_revert(i, copied); return false; } size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
