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    Subject[ 50/57] drm/radeon: Make r100_cp_ring_info() and radeon_ring_gfx() safe (v2)
    Date
    3.11-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Alex Ivanov <gnidorah@p0n4ik.tk>

    commit 0eb3448aa6b31fbf24c31756aba7940cac5ad6b8 upstream.

    Prevent NULL pointer dereference in case when radeon_ring_fini() did it's job.

    Reading of r100_cp_ring_info and radeon_ring_gfx debugfs entries will lead to a KP if ring buffer was deallocated, e.g. on failed ring test.
    Seen on PA-RISC machine having "radeon: ring test failed (scratch(0x8504)=0xCAFEDEAD)" issue.

    v2: agd5f: add some parens around ring->ready check

    Signed-off-by: Alex Ivanov <gnidorah@p0n4ik.tk>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/gpu/drm/radeon/r100.c | 8 +++++---
    drivers/gpu/drm/radeon/radeon_ring.c | 8 +++++---
    2 files changed, 10 insertions(+), 6 deletions(-)

    --- a/drivers/gpu/drm/radeon/r100.c
    +++ b/drivers/gpu/drm/radeon/r100.c
    @@ -2926,9 +2926,11 @@ static int r100_debugfs_cp_ring_info(str
    seq_printf(m, "CP_RB_RPTR 0x%08x\n", rdp);
    seq_printf(m, "%u free dwords in ring\n", ring->ring_free_dw);
    seq_printf(m, "%u dwords in ring\n", count);
    - for (j = 0; j <= count; j++) {
    - i = (rdp + j) & ring->ptr_mask;
    - seq_printf(m, "r[%04d]=0x%08x\n", i, ring->ring[i]);
    + if (ring->ready) {
    + for (j = 0; j <= count; j++) {
    + i = (rdp + j) & ring->ptr_mask;
    + seq_printf(m, "r[%04d]=0x%08x\n", i, ring->ring[i]);
    + }
    }
    return 0;
    }
    --- a/drivers/gpu/drm/radeon/radeon_ring.c
    +++ b/drivers/gpu/drm/radeon/radeon_ring.c
    @@ -846,9 +846,11 @@ static int radeon_debugfs_ring_info(stru
    * packet that is the root issue
    */
    i = (ring->rptr + ring->ptr_mask + 1 - 32) & ring->ptr_mask;
    - for (j = 0; j <= (count + 32); j++) {
    - seq_printf(m, "r[%5d]=0x%08x\n", i, ring->ring[i]);
    - i = (i + 1) & ring->ptr_mask;
    + if (ring->ready) {
    + for (j = 0; j <= (count + 32); j++) {
    + seq_printf(m, "r[%5d]=0x%08x\n", i, ring->ring[i]);
    + i = (i + 1) & ring->ptr_mask;
    + }
    }
    return 0;
    }



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