On Tue, Nov 12, 2024 at 03:04:22PM -0800, Peter Collingbourne wrote:
On Wed, Nov 06, 2024 at 01:05:55PM +0100, Greg Kroah-Hartman wrote:
5.4-stable review patch. If anyone has any objections, please let me know.
From: Qun-Wei Lin qun-wei.lin@mediatek.com
commit 704573851b51808b45dae2d62059d1d8189138a2 upstream.
This patch addresses an issue introduced by commit 1a83a716ec233 ("mm: krealloc: consider spare memory for __GFP_ZERO") which causes MTE (Memory Tagging Extension) to falsely report a slab-out-of-bounds error.
The problem occurs when zeroing out spare memory in __do_krealloc. The original code only considered software-based KASAN and did not account for MTE. It does not reset the KASAN tag before calling memset, leading to a mismatch between the pointer tag and the memory tag, resulting in a false positive.
Example of the error:
swapper/0: BUG: KASAN: slab-out-of-bounds in __memset+0x84/0x188 swapper/0: Write at addr f4ffff8005f0fdf0 by task swapper/0/1 swapper/0: Pointer tag: [f4], memory tag: [fe] swapper/0: swapper/0: CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12. swapper/0: Hardware name: MT6991(ENG) (DT) swapper/0: Call trace: swapper/0: dump_backtrace+0xfc/0x17c swapper/0: show_stack+0x18/0x28 swapper/0: dump_stack_lvl+0x40/0xa0 swapper/0: print_report+0x1b8/0x71c swapper/0: kasan_report+0xec/0x14c swapper/0: __do_kernel_fault+0x60/0x29c swapper/0: do_bad_area+0x30/0xdc swapper/0: do_tag_check_fault+0x20/0x34 swapper/0: do_mem_abort+0x58/0x104 swapper/0: el1_abort+0x3c/0x5c swapper/0: el1h_64_sync_handler+0x80/0xcc swapper/0: el1h_64_sync+0x68/0x6c swapper/0: __memset+0x84/0x188 swapper/0: btf_populate_kfunc_set+0x280/0x3d8 swapper/0: __register_btf_kfunc_id_set+0x43c/0x468 swapper/0: register_btf_kfunc_id_set+0x48/0x60 swapper/0: register_nf_nat_bpf+0x1c/0x40 swapper/0: nf_nat_init+0xc0/0x128 swapper/0: do_one_initcall+0x184/0x464 swapper/0: do_initcall_level+0xdc/0x1b0 swapper/0: do_initcalls+0x70/0xc0 swapper/0: do_basic_setup+0x1c/0x28 swapper/0: kernel_init_freeable+0x144/0x1b8 swapper/0: kernel_init+0x20/0x1a8 swapper/0: ret_from_fork+0x10/0x20 ==================================================================
Fixes: 1a83a716ec233 ("mm: krealloc: consider spare memory for __GFP_ZERO") Signed-off-by: Qun-Wei Lin qun-wei.lin@mediatek.com Acked-by: David Rientjes rientjes@google.com Signed-off-by: Vlastimil Babka vbabka@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
mm/slab_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Hi Greg,
Can this be picked up for the other stable trees as well please? The patch that caused MTE false positives is in linux-5.10.y, linux-5.15.y, linux-6.1.y and linux-6.6.y but this fix is not. I checked that it applies cleanly to all of them.
Yes, that's odd it only went to 5.4.y, something must have gone wonky with Sasha's scripts here and we didn't catch that in review, sorry.
Now queued up, thanks!
greg k-h