[PATCH 4.2.y-ckt 231/305] s390/dis: Fix handling of format specifiers
From: Kamal Mostafa
Date: Fri Jan 15 2016 - 19:06:46 EST
4.2.8-ckt2 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
commit 272fa59ccb4fc802af28b1d699c2463db6a71bf7 upstream.
The print_insn() function returns strings like "lghi %r1,0". To escape the
'%' character in sprintf() a second '%' is used. For example "lghi %%r1,0"
is converted into "lghi %r1,0".
After print_insn() the output string is passed to printk(). Because format
specifiers like "%r" or "%f" are ignored by printk() this works by chance
most of the time. But for instructions with control registers like
"lctl %c6,%c6,780" this fails because printk() interprets "%c" as
character format specifier.
Fix this problem and escape the '%' characters twice.
For example "lctl %%%%c6,%%%%c6,780" is then converted by sprintf()
into "lctl %%c6,%%c6,780" and by printk() into "lctl %c6,%c6,780".
Signed-off-by: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
arch/s390/kernel/dis.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c
index 8140d10..6e72961 100644
--- a/arch/s390/kernel/dis.c
+++ b/arch/s390/kernel/dis.c
@@ -1920,16 +1920,23 @@ static int print_insn(char *buffer, unsigned char *code, unsigned long addr)
}
if (separator)
ptr += sprintf(ptr, "%c", separator);
+ /*
+ * Use four '%' characters below because of the
+ * following two conversions:
+ *
+ * 1) sprintf: %%%%r -> %%r
+ * 2) printk : %%r -> %r
+ */
if (operand->flags & OPERAND_GPR)
- ptr += sprintf(ptr, "%%r%i", value);
+ ptr += sprintf(ptr, "%%%%r%i", value);
else if (operand->flags & OPERAND_FPR)
- ptr += sprintf(ptr, "%%f%i", value);
+ ptr += sprintf(ptr, "%%%%f%i", value);
else if (operand->flags & OPERAND_AR)
- ptr += sprintf(ptr, "%%a%i", value);
+ ptr += sprintf(ptr, "%%%%a%i", value);
else if (operand->flags & OPERAND_CR)
- ptr += sprintf(ptr, "%%c%i", value);
+ ptr += sprintf(ptr, "%%%%c%i", value);
else if (operand->flags & OPERAND_VR)
- ptr += sprintf(ptr, "%%v%i", value);
+ ptr += sprintf(ptr, "%%%%v%i", value);
else if (operand->flags & OPERAND_PCREL)
ptr += sprintf(ptr, "%lx", (signed int) value
+ addr);
--
1.9.1