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Commit fc5aeeaf authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Linus Torvalds
Browse files

mm/kasan: prevent deadlock in kasan reporting 



When we end up calling kasan_report in real mode, our shadow mapping for
the spinlock variable will show poisoned.  This will result in us calling
kasan_report_error with lock_report spin lock held.  To prevent this
disable kasan reporting when we are priting error w.r.t kasan.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: default avatarAndrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f2377d4e

mm/kasan/report.c

+10 −2
Original line number Diff line number Diff line
@@ -173,12 +173,10 @@ static void print_shadow_for_address(const void *addr) 
		 * function, because generic functions may try to

		 * access kasan mapping for the passed address.

		 */

		kasan_disable_current();

		memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);

		print_hex_dump(KERN_ERR, buffer,

			DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,

			shadow_buf, SHADOW_BYTES_PER_ROW, 0);

		kasan_enable_current();



		if (row_is_guilty(shadow_row, shadow))

			pr_err("%*c\n",
@@ -195,6 +193,10 @@ void kasan_report_error(struct kasan_access_info *info) 
{

	unsigned long flags;



	/*

	 * Make sure we don't end up in loop.

	 */

	kasan_disable_current();

	spin_lock_irqsave(&report_lock, flags);

	pr_err("================================="

		"=================================\n");
@@ -204,12 +206,17 @@ void kasan_report_error(struct kasan_access_info *info) 
	pr_err("================================="

		"=================================\n");

	spin_unlock_irqrestore(&report_lock, flags);

	kasan_enable_current();

}



void kasan_report_user_access(struct kasan_access_info *info)

{

	unsigned long flags;



	/*

	 * Make sure we don't end up in loop.

	 */

	kasan_disable_current();

	spin_lock_irqsave(&report_lock, flags);

	pr_err("================================="

		"=================================\n");
@@ -222,6 +229,7 @@ void kasan_report_user_access(struct kasan_access_info *info) 
	pr_err("================================="

		"=================================\n");

	spin_unlock_irqrestore(&report_lock, flags);

	kasan_enable_current();

}



void kasan_report(unsigned long addr, size_t size,