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authorManinder Singh <maninder1.s@samsung.com>2021-05-06 18:06:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-07 00:26:34 -0700
commit5aa6b70ed182549cae9c7ebb48820c42ffaf2eb1 (patch)
treeecf1644d3470ba09fd7346301363f603e32245ec
parentf7c8ce44ebb113b83135ada6e496db33d8a535e3 (diff)
arm: print alloc free paths for address in registers
In case of a use after free kernel oops, the freeing path of the object is required to debug futher. In most of cases the object address is present in one of the registers. Thus check the register's address and if it belongs to slab, print its alloc and free path. e.g. in the below issue register r6 belongs to slab, and a use after free issue occurred on one of its dereferenced values: Unable to handle kernel paging request at virtual address 6b6b6b6f .... pc : [<c0538afc>] lr : [<c0465674>] psr: 60000013 sp : c8927d40 ip : ffffefff fp : c8aa8020 r10: c8927e10 r9 : 00000001 r8 : 00400cc0 r7 : 00000000 r6 : c8ab0180 r5 : c1804a80 r4 : c8aa8008 r3 : c1a5661c r2 : 00000000 r1 : 6b6b6b6b r0 : c139bf48 ..... Register r6 information: slab kmalloc-64 start c8ab0140 data offset 64 pointer offset 0 size 64 allocated at meminfo_proc_show+0x40/0x4fc meminfo_proc_show+0x40/0x4fc seq_read_iter+0x18c/0x4c4 proc_reg_read_iter+0x84/0xac generic_file_splice_read+0xe8/0x17c splice_direct_to_actor+0xb8/0x290 do_splice_direct+0xa0/0xe0 do_sendfile+0x2d0/0x438 sys_sendfile64+0x12c/0x140 ret_fast_syscall+0x0/0x58 0xbeeacde4 Free path: meminfo_proc_show+0x5c/0x4fc seq_read_iter+0x18c/0x4c4 proc_reg_read_iter+0x84/0xac generic_file_splice_read+0xe8/0x17c splice_direct_to_actor+0xb8/0x290 do_splice_direct+0xa0/0xe0 do_sendfile+0x2d0/0x438 sys_sendfile64+0x12c/0x140 ret_fast_syscall+0x0/0x58 0xbeeacde4 Link: https://lkml.kernel.org/r/1615891032-29160-3-git-send-email-maninder1.s@samsung.com Co-developed-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/arm/include/asm/bug.h1
-rw-r--r--arch/arm/kernel/process.c11
-rw-r--r--arch/arm/kernel/traps.c1
3 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm/include/asm/bug.h b/arch/arm/include/asm/bug.h
index 673c7dd75ab9..ba8d9d7d242b 100644
--- a/arch/arm/include/asm/bug.h
+++ b/arch/arm/include/asm/bug.h
@@ -88,5 +88,6 @@ extern asmlinkage void c_backtrace(unsigned long fp, int pmode,
struct mm_struct;
void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr);
extern void __show_regs(struct pt_regs *);
+extern void __show_regs_alloc_free(struct pt_regs *regs);
#endif
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 5199a2bb4111..6324f4db9b02 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -92,6 +92,17 @@ void arch_cpu_idle_exit(void)
ledtrig_cpu(CPU_LED_IDLE_END);
}
+void __show_regs_alloc_free(struct pt_regs *regs)
+{
+ int i;
+
+ /* check for r0 - r12 only */
+ for (i = 0; i < 13; i++) {
+ pr_alert("Register r%d information:", i);
+ mem_dump_obj((void *)regs->uregs[i]);
+ }
+}
+
void __show_regs(struct pt_regs *regs)
{
unsigned long flags;
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 17d5a785df28..64308e3a5d0c 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -287,6 +287,7 @@ static int __die(const char *str, int err, struct pt_regs *regs)
print_modules();
__show_regs(regs);
+ __show_regs_alloc_free(regs);
pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));