From e2a26253921920861f17fffcab1ec926807ad2ae Mon Sep 17 00:00:00 2001 From: Daniel Thompson Date: Fri, 28 Jan 2022 14:40:55 +0000 Subject: kdb: Fix the putarea helper function [ Upstream commit c1cb81429df462eca1b6ba615cddd21dd3103c46 ] Currently kdb_putarea_size() uses copy_from_kernel_nofault() to write *to* arbitrary kernel memory. This is obviously wrong and means the memory modify ('mm') command is a serious risk to debugger stability: if we poke to a bad address we'll double-fault and lose our debug session. Fix this the (very) obvious way. Note that there are two Fixes: tags because the API was renamed and this patch will only trivially backport as far as the rename (and this is probably enough). Nevertheless Christoph's rename did not introduce this problem so I wanted to record that! Fixes: fe557319aa06 ("maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault") Fixes: 5d5314d6795f ("kdb: core for kgdb back end (1 of 2)") Signed-off-by: Daniel Thompson Reviewed-by: Douglas Anderson Link: https://lore.kernel.org/r/20220128144055.207267-1-daniel.thompson@linaro.org Signed-off-by: Sasha Levin --- kernel/debug/kdb/kdb_support.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/debug') diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c index 6226502ce049..13417f0045f0 100644 --- a/kernel/debug/kdb/kdb_support.c +++ b/kernel/debug/kdb/kdb_support.c @@ -350,7 +350,7 @@ int kdb_getarea_size(void *res, unsigned long addr, size_t size) */ int kdb_putarea_size(unsigned long addr, void *res, size_t size) { - int ret = copy_from_kernel_nofault((char *)addr, (char *)res, size); + int ret = copy_to_kernel_nofault((char *)addr, (char *)res, size); if (ret) { if (!KDB_STATE(SUPPRESS)) { kdb_printf("kdb_putarea: Bad address 0x%lx\n", addr); -- cgit v1.2.3