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Zack RusinandGreg Kroah-Hartman
58a3714db4
commitaba07b9a05upstream. The kms paths keep a persistent map active to read and compare the cursor buffer. These maps can race with each other in simple scenario where: a) buffer "a" mapped for update b) buffer "a" mapped for compare c) do the compare d) unmap "a" for compare e) update the cursor f) unmap "a" for update At step "e" the buffer has been unmapped and the read contents is bogus. Prevent unmapping of active read buffers by simply keeping a count of how many paths have currently active maps and unmap only when the count reaches 0. Fixes:485d98d472("drm/vmwgfx: Add support for CursorMob and CursorBypass 4") Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com> Cc: dri-devel@lists.freedesktop.org Cc: <stable@vger.kernel.org> # v5.19+ Signed-off-by: Zack Rusin <zack.rusin@broadcom.com> Link: https://patchwork.freedesktop.org/patch/msgid/20240816183332.31961-2-zack.rusin@broadcom.com Reviewed-by: Martin Krastev <martin.krastev@broadcom.com> Reviewed-by: Maaz Mombasawala <maaz.mombasawala@broadcom.com> [Shivani: Modified to apply on v6.1.y] Signed-off-by: Shivani Agarwal <shivani.agarwal@broadcom.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>