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authorPawan Gupta <pawan.kumar.gupta@linux.intel.com>2024-09-26 00:25:38 +0200
committerDave Hansen <dave.hansen@linux.intel.com>2024-10-09 00:16:28 +0200
commit2e2e5143d4868163d6756c8c6a4d28cbfa5245e5 (patch)
treed95b4beb2e7f5662dad93cfa0a864f139ee052ed /arch
parentx86/resctrl: Annotate get_mem_config() functions as __init (diff)
downloadlinux-2e2e5143d4868163d6756c8c6a4d28cbfa5245e5.tar.xz
linux-2e2e5143d4868163d6756c8c6a4d28cbfa5245e5.zip
x86/entry_32: Do not clobber user EFLAGS.ZF
Opportunistic SYSEXIT executes VERW to clear CPU buffers after user EFLAGS are restored. This can clobber user EFLAGS.ZF. Move CLEAR_CPU_BUFFERS before the user EFLAGS are restored. This ensures that the user EFLAGS.ZF is not clobbered. Closes: https://lore.kernel.org/lkml/yVXwe8gvgmPADpRB6lXlicS2fcHoV5OHHxyuFbB_MEleRPD7-KhGe5VtORejtPe-KCkT8Uhcg5d7-IBw4Ojb4H7z5LQxoZylSmJ8KNL3A8o=@protonmail.com/ Fixes: a0e2dab44d22 ("x86/entry_32: Add VERW just before userspace transition") Reported-by: Jari Ruusu <jariruusu@protonmail.com> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20240925-fix-dosemu-vm86-v7-1-1de0daca2d42%40linux.intel.com
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/entry/entry_32.S3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index d3a814efbff6..9ad6cd89b7ac 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -871,6 +871,8 @@ SYM_FUNC_START(entry_SYSENTER_32)
/* Now ready to switch the cr3 */
SWITCH_TO_USER_CR3 scratch_reg=%eax
+ /* Clobbers ZF */
+ CLEAR_CPU_BUFFERS
/*
* Restore all flags except IF. (We restore IF separately because
@@ -881,7 +883,6 @@ SYM_FUNC_START(entry_SYSENTER_32)
BUG_IF_WRONG_CR3 no_user_check=1
popfl
popl %eax
- CLEAR_CPU_BUFFERS
/*
* Return back to the vDSO, which will pop ecx and edx.