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    Subject[PATCH 3.13.y-ckt 072/108] s390/dis: Fix handling of format specifiers
    Date
    3.13.11-ckt33 -stable review patch.  If anyone has any objections, please let me know.

    ---8<------------------------------------------------------------

    From: Michael Holzheu <holzheu@linux.vnet.ibm.com>

    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@linux.vnet.ibm.com>
    Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
    [ luis: backported to 3.16:
    - drop condition with OPERAND_VR introduced only with commit
    3585cb028065 ("s390/disassembler: add vector instructions") ]
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    arch/s390/kernel/dis.c | 15 +++++++++++----
    1 file changed, 11 insertions(+), 4 deletions(-)

    diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c
    index 993efe6..3d94231 100644
    --- a/arch/s390/kernel/dis.c
    +++ b/arch/s390/kernel/dis.c
    @@ -1726,14 +1726,21 @@ 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_PCREL)
    ptr += sprintf(ptr, "%lx", (signed int) value
    + addr);
    --
    1.9.1
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