diff options
| author | Qian Cai <cai@lca.pw> | 2019-04-23 12:58:11 -0400 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2019-04-24 11:32:34 +0200 |
| commit | 0d02113b31b2017dd349ec9df2314e798a90fa6e (patch) | |
| tree | 46e965be16d06e42c150950286f05f3797c64ccb | |
| parent | 36f0c423552dacaca152324b8e9bda42a6d88865 (diff) | |
x86/mm: Fix a crash with kmemleak_scan()
The first kmemleak_scan() call after boot would trigger the crash below
because this callpath:
kernel_init
free_initmem
mem_encrypt_free_decrypted_mem
free_init_pages
unmaps memory inside the .bss when DEBUG_PAGEALLOC=y.
kmemleak_init() will register the .data/.bss sections and then
kmemleak_scan() will scan those addresses and dereference them looking
for pointer references. If free_init_pages() frees and unmaps pages in
those sections, kmemleak_scan() will crash if referencing one of those
addresses:
BUG: unable to handle kernel paging request at ffffffffbd402000
CPU: 12 PID: 325 Comm: kmemleak Not tainted 5.1.0-rc4+ #4
RIP: 0010:scan_block
Call Trace:
scan_gray_list
kmemleak_scan
kmemleak_scan_thread
kthread
ret_from_fork
Since kmemleak_free_part() is tolerant to unknown objects (not tracked
by kmemleak), it is fine to call it from free_init_pages() even if not
all address ranges passed to this function are known to kmemleak.
[ bp: Massage. ]
Fixes: b3f0907c71e0 ("x86/mm: Add .bss..decrypted section to hold shared variables")
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190423165811.36699-1-cai@lca.pw
| -rw-r--r-- | arch/x86/mm/init.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index f905a2371080..8dacdb96899e 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -5,6 +5,7 @@ #include <linux/memblock.h> #include <linux/swapfile.h> #include <linux/swapops.h> +#include <linux/kmemleak.h> #include <asm/set_memory.h> #include <asm/e820/api.h> @@ -766,6 +767,11 @@ void free_init_pages(const char *what, unsigned long begin, unsigned long end) if (debug_pagealloc_enabled()) { pr_info("debug: unmapping init [mem %#010lx-%#010lx]\n", begin, end - 1); + /* + * Inform kmemleak about the hole in the memory since the + * corresponding pages will be unmapped. + */ + kmemleak_free_part((void *)begin, end - begin); set_memory_np(begin, (end - begin) >> PAGE_SHIFT); } else { /* |