Buildresult: linus/i386-allnoconfig/i386-gcc4.6 built on Mar 12 2020, 03:56

kisskb

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Status:	OK
Date/Time:	Mar 12 2020, 03:56
Duration:	0:00:19.145910
Builder:	ka3
Revision:	driver code: clarify and fix platform device DMA mask allocation (`e3a36eb6dfaeea8175c05d5915dcf0b939be6dab)`
Target:	linus/i386-allnoconfig/i386-gcc4.6
Branch:	linus
Compiler:	i386-gcc4.6 (i386-linux-gcc (GCC) 4.6.3 / GNU ld (GNU Binutils) 2.22)
Config:	allnoconfig (download)
Log:	Download original Possible warnings (2) kernel/printk/printk.c:204:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] arch/x86/kernel/e820.c:665:16: warning: 'gapstart' may be used uninitialized in this function [-Wuninitialized] Full Log # 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 <hch@lst.de> # 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 <aros@gmx.com> # Reviewed-by: Robin Murphy <robin.murphy@arm.com> # Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> # Signed-off-by: Christoph Hellwig <hch@lst.de> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux-ld --version # < git log --format=%s --max-count=1 e3a36eb6dfaeea8175c05d5915dcf0b939be6dab # < make -s -j 80 ARCH=i386 O=/kisskb/build/linus_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- allnoconfig # < make -s -j 80 ARCH=i386 O=/kisskb/build/linus_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- help # make -s -j 80 ARCH=i386 O=/kisskb/build/linus_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- olddefconfig # make -s -j 80 ARCH=i386 O=/kisskb/build/linus_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-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/arch/x86/kernel/e820.c: In function 'e820__setup_pci_gap': /kisskb/src/arch/x86/kernel/e820.c:665:16: warning: 'gapstart' may be used uninitialized in this function [-Wuninitialized] Completed OK # rm -rf /kisskb/build/linus_i386-allnoconfig_i386-gcc4.6 # Build took: 0:00:19.145910

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