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f6dc6b54ba
It is necessary to reset the error pointer after error_report_err(), because that function frees the error. Not doing so can lead to a use-after-free and in particular error_setg() with the same error pointer will run into assertion failure, because it asserts that no previous error is set: > #5 0x00007c1723674eb2 in __GI___assert_fail (assertion=assertion@entry=0x59132c9fc540 "*errp == NULL", > file=file@entry=0x59132c9fc530 "../util/error.c", line=line@entry=68, > function=function@entry=0x59132c9fc5f8 <__PRETTY_FUNCTION__.2> "error_setv") > #6 0x000059132c7d250f in error_setv (errp=0x7c15839fafb8, src=0x59132c9af224 "../block/dirty-bitmap.c", line=182, > func=0x59132c9af9b0 <__func__.17> "bdrv_dirty_bitmap_check", err_class=err_class@entry=ERROR_CLASS_GENERIC_ERROR, > fmt=fmt@entry=0x59132c9af380 "Bitmap '%s' is currently in use by another operation and cannot be used", ap=0x7c15839fad60, > suffix=0x0) > #7 0x000059132c7d265c in error_setg_internal (errp=errp@entry=0x7c15839fafb8, > src=src@entry=0x59132c9af224 "../block/dirty-bitmap.c", line=line@entry=182, > func=func@entry=0x59132c9af9b0 <__func__.17> "bdrv_dirty_bitmap_check", > fmt=fmt@entry=0x59132c9af380 "Bitmap '%s' is currently in use by another operation and cannot be used") > #8 0x000059132c68fbc1 in bdrv_dirty_bitmap_check (bitmap=bitmap@entry=0x5913542d6190, flags=flags@entry=7, > errp=errp@entry=0x7c15839fafb8) > #9 0x000059132c3b951d in add_bitmaps_to_list (s=s@entry=0x59132d87ee40 <dbm_state>, bs=bs@entry=0x591352d6b720, > bs_name=bs_name@entry=0x591352d69900 "drive-scsi1", alias_map=alias_map@entry=0x0, errp=errp@entry=0x7c15839fafb8) > #10 0x000059132c3ba23d in init_dirty_bitmap_migration (errp=<optimized out>, s=0x59132d87ee40 <dbm_state>) > #11 dirty_bitmap_save_setup (f=0x591352ebdd30, opaque=0x59132d87ee40 <dbm_state>, errp=0x7c15839fafb8) > #12 0x000059132c3d81f0 in qemu_savevm_state_setup (f=0x591352ebdd30, errp=errp@entry=0x7c15839fafb8) Fix created using the appropriate in-tree coccinelle script: spatch --in-place scripts/coccinelle/error-use-after-free.cocci migration/block-dirty-bitmap.c The problematic change exposing the issue was part of 7882afe ("update submodule and patches to QEMU 9.1.2") adapting to QEMU 9.1, commit dd03167725 ("migration: Add Error** argument to add_bitmaps_to_list()"), where the add_bitmaps_to_list() function gained an error pointer argument, replacing the local error variable that was used before. Fixes: 7882afe ("update submodule and patches to QEMU 9.1.2") Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>