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 --- tools/perf/util/cloexec.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 tools/perf/util/cloexec.c (limited to 'tools/perf/util/cloexec.c') diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c new file mode 100644 index 000000000..8830604c3 --- /dev/null +++ b/tools/perf/util/cloexec.c @@ -0,0 +1,92 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include "util.h" // for sched_getcpu() +#include "../perf-sys.h" +#include "cloexec.h" +#include "event.h" +#include "asm/bug.h" +#include "debug.h" +#include +#include +#include + +static unsigned long flag = PERF_FLAG_FD_CLOEXEC; + +static int perf_flag_probe(void) +{ + /* use 'safest' configuration as used in evsel__fallback() */ + struct perf_event_attr attr = { + .type = PERF_TYPE_SOFTWARE, + .config = PERF_COUNT_SW_CPU_CLOCK, + .exclude_kernel = 1, + }; + int fd; + int err; + int cpu; + pid_t pid = -1; + char sbuf[STRERR_BUFSIZE]; + + cpu = sched_getcpu(); + if (cpu < 0) + cpu = 0; + + /* + * Using -1 for the pid is a workaround to avoid gratuitous jump label + * changes. + */ + while (1) { + /* check cloexec flag */ + fd = sys_perf_event_open(&attr, pid, cpu, -1, + PERF_FLAG_FD_CLOEXEC); + if (fd < 0 && pid == -1 && errno == EACCES) { + pid = 0; + continue; + } + break; + } + err = errno; + + if (fd >= 0) { + close(fd); + return 1; + } + + WARN_ONCE(err != EINVAL && err != EBUSY && err != EACCES, + "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n", + err, str_error_r(err, sbuf, sizeof(sbuf))); + + /* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */ + while (1) { + fd = sys_perf_event_open(&attr, pid, cpu, -1, 0); + if (fd < 0 && pid == -1 && errno == EACCES) { + pid = 0; + continue; + } + break; + } + err = errno; + + if (fd >= 0) + close(fd); + + if (WARN_ONCE(fd < 0 && err != EBUSY && err != EACCES, + "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n", + err, str_error_r(err, sbuf, sizeof(sbuf)))) + return -1; + + return 0; +} + +unsigned long perf_event_open_cloexec_flag(void) +{ + static bool probed; + + if (!probed) { + if (perf_flag_probe() <= 0) + flag = 0; + probed = true; + } + + return flag; +} -- cgit v1.3.1