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s390/dis: Fix handling of format specifiers 

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@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Michael Holzheu 2015-12-17 19:06:02 +01:00 committed by Martin Schwidefsky
parent 2bc53b8046
commit 272fa59ccb
1 changed files with 12 additions and 5 deletions
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17
arch/s390/kernel/dis.c
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@ -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);