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    Subject[PATCH] [14/106] ROSE: prevent heap corruption with bad facilities
    Date
    2.6.35-longterm review patch.  If anyone has any objections, please let me know.

    ------------------
    From: Dan Rosenberg <drosenberg@vsecurity.com>

    commit be20250c13f88375345ad99950190685eda51eb8 upstream.

    When parsing the FAC_NATIONAL_DIGIS facilities field, it's possible for
    a remote host to provide more digipeaters than expected, resulting in
    heap corruption. Check against ROSE_MAX_DIGIS to prevent overflows, and
    abort facilities parsing on failure.

    Additionally, when parsing the FAC_CCITT_DEST_NSAP and
    FAC_CCITT_SRC_NSAP facilities fields, a remote host can provide a length
    of less than 10, resulting in an underflow in a memcpy size, causing a
    kernel panic due to massive heap corruption. A length of greater than
    20 results in a stack overflow of the callsign array. Abort facilities
    parsing on these invalid length values.

    Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    Signed-off-by: Andi Kleen <ak@linux.intel.com>

    ---
    net/rose/rose_subr.c | 18 ++++++++++++++++--
    1 file changed, 16 insertions(+), 2 deletions(-)

    Index: linux-2.6.35.y/net/rose/rose_subr.c
    ===================================================================
    --- linux-2.6.35.y.orig/net/rose/rose_subr.c
    +++ linux-2.6.35.y/net/rose/rose_subr.c
    @@ -290,10 +290,15 @@ static int rose_parse_national(unsigned
    facilities->source_ndigis = 0;
    facilities->dest_ndigis = 0;
    for (pt = p + 2, lg = 0 ; lg < l ; pt += AX25_ADDR_LEN, lg += AX25_ADDR_LEN) {
    - if (pt[6] & AX25_HBIT)
    + if (pt[6] & AX25_HBIT) {
    + if (facilities->dest_ndigis >= ROSE_MAX_DIGIS)
    + return -1;
    memcpy(&facilities->dest_digis[facilities->dest_ndigis++], pt, AX25_ADDR_LEN);
    - else
    + } else {
    + if (facilities->source_ndigis >= ROSE_MAX_DIGIS)
    + return -1;
    memcpy(&facilities->source_digis[facilities->source_ndigis++], pt, AX25_ADDR_LEN);
    + }
    }
    }
    p += l + 2;
    @@ -333,6 +338,11 @@ static int rose_parse_ccitt(unsigned cha

    case 0xC0:
    l = p[1];
    +
    + /* Prevent overflows*/
    + if (l < 10 || l > 20)
    + return -1;
    +
    if (*p == FAC_CCITT_DEST_NSAP) {
    memcpy(&facilities->source_addr, p + 7, ROSE_ADDR_LEN);
    memcpy(callsign, p + 12, l - 10);
    @@ -373,12 +383,16 @@ int rose_parse_facilities(unsigned char
    switch (*p) {
    case FAC_NATIONAL: /* National */
    len = rose_parse_national(p + 1, facilities, facilities_len - 1);
    + if (len < 0)
    + return 0;
    facilities_len -= len + 1;
    p += len + 1;
    break;

    case FAC_CCITT: /* CCITT */
    len = rose_parse_ccitt(p + 1, facilities, facilities_len - 1);
    + if (len < 0)
    + return 0;
    facilities_len -= len + 1;
    p += len + 1;
    break;

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