lkml.org 
[lkml]   [2020]   [Dec]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 24/39] x86/uprobes: Do not use prefixes.nbytes when looping over prefixes.bytes
    Date
    From: Masami Hiramatsu <mhiramat@kernel.org>

    commit 4e9a5ae8df5b3365183150f6df49e49dece80d8c upstream.

    Since insn.prefixes.nbytes can be bigger than the size of
    insn.prefixes.bytes[] when a prefix is repeated, the proper check must
    be

    insn.prefixes.bytes[i] != 0 and i < 4

    instead of using insn.prefixes.nbytes.

    Introduce a for_each_insn_prefix() macro for this purpose. Debugged by
    Kees Cook <keescook@chromium.org>.

    [ bp: Massage commit message, sync with the respective header in tools/
    and drop "we". ]

    Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints")
    Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com
    Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Cc: stable@vger.kernel.org
    Link: https://lkml.kernel.org/r/160697103739.3146288.7437620795200799020.stgit@devnote2
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/include/asm/insn.h | 15 +++++++++++++++
    arch/x86/kernel/uprobes.c | 10 ++++++----
    tools/objtool/arch/x86/include/asm/insn.h | 15 +++++++++++++++
    tools/perf/util/intel-pt-decoder/insn.h | 15 +++++++++++++++
    4 files changed, 51 insertions(+), 4 deletions(-)

    --- a/arch/x86/include/asm/insn.h
    +++ b/arch/x86/include/asm/insn.h
    @@ -208,6 +208,21 @@ static inline int insn_offset_immediate(
    return insn_offset_displacement(insn) + insn->displacement.nbytes;
    }

    +/**
    + * for_each_insn_prefix() -- Iterate prefixes in the instruction
    + * @insn: Pointer to struct insn.
    + * @idx: Index storage.
    + * @prefix: Prefix byte.
    + *
    + * Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
    + * and the index is stored in @idx (note that this @idx is just for a cursor,
    + * do not change it.)
    + * Since prefixes.nbytes can be bigger than 4 if some prefixes
    + * are repeated, it cannot be used for looping over the prefixes.
    + */
    +#define for_each_insn_prefix(insn, idx, prefix) \
    + for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
    +
    #define POP_SS_OPCODE 0x1f
    #define MOV_SREG_OPCODE 0x8e

    --- a/arch/x86/kernel/uprobes.c
    +++ b/arch/x86/kernel/uprobes.c
    @@ -268,12 +268,13 @@ static volatile u32 good_2byte_insns[256

    static bool is_prefix_bad(struct insn *insn)
    {
    + insn_byte_t p;
    int i;

    - for (i = 0; i < insn->prefixes.nbytes; i++) {
    + for_each_insn_prefix(insn, i, p) {
    insn_attr_t attr;

    - attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]);
    + attr = inat_get_opcode_attribute(p);
    switch (attr) {
    case INAT_MAKE_PREFIX(INAT_PFX_ES):
    case INAT_MAKE_PREFIX(INAT_PFX_CS):
    @@ -728,6 +729,7 @@ static const struct uprobe_xol_ops push_
    static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
    {
    u8 opc1 = OPCODE1(insn);
    + insn_byte_t p;
    int i;

    switch (opc1) {
    @@ -758,8 +760,8 @@ static int branch_setup_xol_ops(struct a
    * Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix.
    * No one uses these insns, reject any branch insns with such prefix.
    */
    - for (i = 0; i < insn->prefixes.nbytes; i++) {
    - if (insn->prefixes.bytes[i] == 0x66)
    + for_each_insn_prefix(insn, i, p) {
    + if (p == 0x66)
    return -ENOTSUPP;
    }

    --- a/tools/objtool/arch/x86/include/asm/insn.h
    +++ b/tools/objtool/arch/x86/include/asm/insn.h
    @@ -208,6 +208,21 @@ static inline int insn_offset_immediate(
    return insn_offset_displacement(insn) + insn->displacement.nbytes;
    }

    +/**
    + * for_each_insn_prefix() -- Iterate prefixes in the instruction
    + * @insn: Pointer to struct insn.
    + * @idx: Index storage.
    + * @prefix: Prefix byte.
    + *
    + * Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
    + * and the index is stored in @idx (note that this @idx is just for a cursor,
    + * do not change it.)
    + * Since prefixes.nbytes can be bigger than 4 if some prefixes
    + * are repeated, it cannot be used for looping over the prefixes.
    + */
    +#define for_each_insn_prefix(insn, idx, prefix) \
    + for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
    +
    #define POP_SS_OPCODE 0x1f
    #define MOV_SREG_OPCODE 0x8e

    --- a/tools/perf/util/intel-pt-decoder/insn.h
    +++ b/tools/perf/util/intel-pt-decoder/insn.h
    @@ -208,6 +208,21 @@ static inline int insn_offset_immediate(
    return insn_offset_displacement(insn) + insn->displacement.nbytes;
    }

    +/**
    + * for_each_insn_prefix() -- Iterate prefixes in the instruction
    + * @insn: Pointer to struct insn.
    + * @idx: Index storage.
    + * @prefix: Prefix byte.
    + *
    + * Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
    + * and the index is stored in @idx (note that this @idx is just for a cursor,
    + * do not change it.)
    + * Since prefixes.nbytes can be bigger than 4 if some prefixes
    + * are repeated, it cannot be used for looping over the prefixes.
    + */
    +#define for_each_insn_prefix(insn, idx, prefix) \
    + for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
    +
    #define POP_SS_OPCODE 0x1f
    #define MOV_SREG_OPCODE 0x8e


    \
     
     \ /
      Last update: 2020-12-10 15:39    [W:4.064 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site