From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- lib/dim/dim.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 lib/dim/dim.c (limited to 'lib/dim/dim.c') diff --git a/lib/dim/dim.c b/lib/dim/dim.c new file mode 100644 index 000000000..97c3d084e --- /dev/null +++ b/lib/dim/dim.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB +/* + * Copyright (c) 2019, Mellanox Technologies inc. All rights reserved. + */ + +#include + +bool dim_on_top(struct dim *dim) +{ + switch (dim->tune_state) { + case DIM_PARKING_ON_TOP: + case DIM_PARKING_TIRED: + return true; + case DIM_GOING_RIGHT: + return (dim->steps_left > 1) && (dim->steps_right == 1); + default: /* DIM_GOING_LEFT */ + return (dim->steps_right > 1) && (dim->steps_left == 1); + } +} +EXPORT_SYMBOL(dim_on_top); + +void dim_turn(struct dim *dim) +{ + switch (dim->tune_state) { + case DIM_PARKING_ON_TOP: + case DIM_PARKING_TIRED: + break; + case DIM_GOING_RIGHT: + dim->tune_state = DIM_GOING_LEFT; + dim->steps_left = 0; + break; + case DIM_GOING_LEFT: + dim->tune_state = DIM_GOING_RIGHT; + dim->steps_right = 0; + break; + } +} +EXPORT_SYMBOL(dim_turn); + +void dim_park_on_top(struct dim *dim) +{ + dim->steps_right = 0; + dim->steps_left = 0; + dim->tired = 0; + dim->tune_state = DIM_PARKING_ON_TOP; +} +EXPORT_SYMBOL(dim_park_on_top); + +void dim_park_tired(struct dim *dim) +{ + dim->steps_right = 0; + dim->steps_left = 0; + dim->tune_state = DIM_PARKING_TIRED; +} +EXPORT_SYMBOL(dim_park_tired); + +bool dim_calc_stats(const struct dim_sample *start, + const struct dim_sample *end, + struct dim_stats *curr_stats) +{ + /* u32 holds up to 71 minutes, should be enough */ + u32 delta_us = ktime_us_delta(end->time, start->time); + u32 npkts = BIT_GAP(BITS_PER_TYPE(u32), end->pkt_ctr, start->pkt_ctr); + u32 nbytes = BIT_GAP(BITS_PER_TYPE(u32), end->byte_ctr, + start->byte_ctr); + u32 ncomps = BIT_GAP(BITS_PER_TYPE(u32), end->comp_ctr, + start->comp_ctr); + + if (!delta_us) + return false; + + curr_stats->ppms = DIV_ROUND_UP(npkts * USEC_PER_MSEC, delta_us); + curr_stats->bpms = DIV_ROUND_UP(nbytes * USEC_PER_MSEC, delta_us); + curr_stats->epms = DIV_ROUND_UP(DIM_NEVENTS * USEC_PER_MSEC, + delta_us); + curr_stats->cpms = DIV_ROUND_UP(ncomps * USEC_PER_MSEC, delta_us); + if (curr_stats->epms != 0) + curr_stats->cpe_ratio = DIV_ROUND_DOWN_ULL( + curr_stats->cpms * 100, curr_stats->epms); + else + curr_stats->cpe_ratio = 0; + + return true; +} +EXPORT_SYMBOL(dim_calc_stats); + +MODULE_DESCRIPTION("Dynamic Interrupt Moderation (DIM) library"); +MODULE_LICENSE("Dual BSD/GPL"); -- cgit v1.3.1