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authorOleg Nesterov <oleg@redhat.com>2012-08-06 13:15:09 +0200
committerOleg Nesterov <oleg@redhat.com>2012-08-28 18:21:16 +0200
commit647c42dfd40fec032a4c8525a755160f0765921f (patch)
treef8bcb634d5cbebcc2168d6834d8a3a27d221c062 /include/linux/uprobes.h
parent8bd874456e2ec49b9e64372ddc89a6f88901d184 (diff)
downloadop-kernel-dev-647c42dfd40fec032a4c8525a755160f0765921f.zip
op-kernel-dev-647c42dfd40fec032a4c8525a755160f0765921f.tar.gz
uprobes: Kill uprobes_state->count
uprobes_state->count is only needed to avoid the slow path in uprobe_pre_sstep_notifier(). It is also checked in uprobe_munmap() but ironically its only goal to decrement this counter. However, it is very broken. Just some examples: - uprobe_mmap() can race with uprobe_unregister() and wrongly increment the counter if it hits the non-uprobe "int3". Note that install_breakpoint() checks ->consumers first and returns -EEXIST if it is NULL. "atomic_sub() if error" in uprobe_mmap() looks obviously wrong too. - uprobe_munmap() can race with uprobe_register() and wrongly decrement the counter by the same reason. - Suppose an appication tries to increase the mmapped area via sys_mremap(). vma_adjust() does uprobe_munmap(whole_vma) first, this can nullify the counter temporarily and race with another thread which can hit the bp, the application will be killed by SIGTRAP. - Suppose an application mmaps 2 consecutive areas in the same file and one (or both) of these areas has uprobes. In the likely case mmap_region()->vma_merge() suceeds. Like above, this leads to uprobe_munmap/uprobe_mmap from vma_merge()->vma_adjust() but then mmap_region() does another uprobe_mmap(resulting_vma) and doubles the counter. This patch only removes this counter and fixes the compile errors, then we will try to cleanup the changed code and add something else instead. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux/uprobes.h')
-rw-r--r--include/linux/uprobes.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index efe4b33..03ae547 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -99,8 +99,8 @@ struct xol_area {
struct uprobes_state {
struct xol_area *xol_area;
- atomic_t count;
};
+
extern int __weak set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr, bool verify);
extern bool __weak is_swbp_insn(uprobe_opcode_t *insn);
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