# git rev-parse -q --verify e3a36eb6dfaeea8175c05d5915dcf0b939be6dab^{commit} e3a36eb6dfaeea8175c05d5915dcf0b939be6dab already have revision, skipping fetch # git checkout -q -f -B kisskb e3a36eb6dfaeea8175c05d5915dcf0b939be6dab # git clean -qxdf # < git log -1 # commit e3a36eb6dfaeea8175c05d5915dcf0b939be6dab # Author: Christoph Hellwig # Date: Wed Mar 11 17:07:10 2020 +0100 # # driver code: clarify and fix platform device DMA mask allocation # # This does three inter-related things to clarify the usage of the # platform device dma_mask field. In the process, fix the bug introduced # by cdfee5623290 ("driver core: initialize a default DMA mask for # platform device") that caused Artem Tashkinov's laptop to not boot with # newer Fedora kernels. # # This does: # # - First off, rename the field to "platform_dma_mask" to make it # greppable. # # We have way too many different random fields called "dma_mask" in # various data structures, where some of them are actual masks, and # some of them are just pointers to the mask. And the structures all # have pointers to each other, or embed each other inside themselves, # and "pdev" sometimes means "platform device" and sometimes it means # "PCI device". # # So to make it clear in the code when you actually use this new field, # give it a unique name (it really should be something even more unique # like "platform_device_dma_mask", since it's per platform device, not # per platform, but that gets old really fast, and this is unique # enough in context). # # To further clarify when the field gets used, initialize it when we # actually start using it with the default value. # # - Then, use this field instead of the random one-off allocation in # platform_device_register_full() that is now unnecessary since we now # already have a perfectly fine allocation for it in the platform # device structure. # # - The above then allows us to fix the actual bug, where the error path # of platform_device_register_full() would unconditionally free the # platform device DMA allocation with 'kfree()'. # # That kfree() was dont regardless of whether the allocation had been # done earlier with the (now removed) kmalloc, or whether # setup_pdev_dma_masks() had already been used and the dma_mask pointer # pointed to the mask that was part of the platform device. # # It seems most people never triggered the error path, or only triggered # it from a call chain that set an explicit pdevinfo->dma_mask value (and # thus caused the unnecessary allocation that was "cleaned up" in the # error path) before calling platform_device_register_full(). # # Robin Murphy points out that in Artem's case the wdat_wdt driver failed # in platform_device_add(), and that was the one that had called # platform_device_register_full() with pdevinfo.dma_mask = 0, and would # have caused that kfree() of pdev.dma_mask corrupting the heap. # # A later unrelated kmalloc() then oopsed due to the heap corruption. # # Fixes: cdfee5623290 ("driver core: initialize a default DMA mask for platform device") # Reported-bisected-and-tested-by: Artem S. Tashkinov # Reviewed-by: Robin Murphy # Cc: Greg Kroah-Hartman # Signed-off-by: Christoph Hellwig # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-ld --version # < git log --format=%s --max-count=1 e3a36eb6dfaeea8175c05d5915dcf0b939be6dab # < make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_pmac32_defconfig+SMP_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- pmac32_defconfig # Added to kconfig CONFIG_SMP=y # < make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_pmac32_defconfig+SMP_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- help # make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_pmac32_defconfig+SMP_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- olddefconfig .config:4058:warning: override: reassigning to symbol SMP # make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_pmac32_defconfig+SMP_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:204:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c: In function 'proc_reg_open': /kisskb/src/include/linux/list.h:72:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c:338:21: note: 'pdeo' was declared here /kisskb/src/fs/ext4/extents.c: In function 'ext4_convert_unwritten_io_end_vec': /kisskb/src/fs/ext4/extents.c:5009:23: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/trace/trace_events.c: In function 'event_create_dir': /kisskb/src/kernel/trace/trace_events.c:2040:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char': /kisskb/src/fs/udf/unicode.c:132:8: warning: 'c' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/sound/ppc/awacs.c: In function 'snd_pmac_awacs_init': /kisskb/src/include/sound/control.h:218:2: warning: 'speaker_vol' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/sound/ppc/awacs.c:873:36: note: 'speaker_vol' was declared here /kisskb/src/fs/nfsd/nfs4xdr.c: In function 'nfsd4_encode_components_esc': /kisskb/src/fs/nfsd/nfs4xdr.c:2151:9: warning: 'str' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq': /kisskb/src/drivers/tty/serial/8250/8250_core.c:247:18: warning: 'i' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/tty/serial/8250/8250_core.c:227:19: note: 'i' was declared here /kisskb/src/fs/io_uring.c: In function '__io_sqe_files_update.isra.65': /kisskb/src/fs/io_uring.c:5845:13: warning: 'err' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c: In function 'tun_get_user': /kisskb/src/drivers/net/tun.c:1836:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1749:46: warning: 'linear' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/usb/core/devio.c: In function 'async_completed': /kisskb/src/drivers/usb/core/devio.c:625:23: warning: 'errno' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/wireless/broadcom/b43/phy_n.c: In function 'b43_nphy_rf_ctl_override_rev7': /kisskb/src/drivers/net/wireless/broadcom/b43/phy_n.c:190:21: warning: 'val_addr' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/gpu/drm/drm_dp_mst_topology.c: In function 'drm_dp_mst_dsc_aux_for_port': /kisskb/src/drivers/gpu/drm/drm_dp_mst_topology.c:5400:9: warning: missing braces around initializer [-Wmissing-braces] /kisskb/src/drivers/gpu/drm/drm_dp_mst_topology.c:5400:9: warning: (near initialization for 'desc.ident') [-Wmissing-braces] /kisskb/src/net/mac80211/mlme.c: In function 'ieee80211_rx_mgmt_beacon': /kisskb/src/net/mac80211/mlme.c:1576:3: warning: 'pwr_level_cisco' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/mac80211/mlme.c:1533:6: note: 'pwr_level_cisco' was declared here INFO: Uncompressed kernel (size 0x8d10a0) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x900000) Completed OK # rm -rf /kisskb/build/linus_pmac32_defconfig+SMP_powerpc-gcc4.6 # Build took: 0:01:23.702452